oop - implementing lists using c# in wpf

OK, to add cars to your List

double noCylinders;
double topSpeed;
double horsePower;
double.TryParse(textBox2.text,out noCylinders);
double.TryParse(textBox3.text,out topSpeed);
double.TryParse(textBox4.text,out horsePower);
b.Add(new Car()
{
   //don't know how to proceed
   cylinders = noCylinders,
   horsepower = horsePower,
   topspeed = topSpeed
});

and then to view each car ike this

foreach(Car car in b)
                {
                    MessageBox.Show("Cylinders = " + car.cylinders +"\n" + "Horsepower = " + car.horsepower + "\n" + "Top speed = " + car.topspeed)
                }

Just a word on naming convention

All classnames should start with a capital, as well as all properties within a class like this

class Car
    {
        public double Cylinders
        {
            get;
            set;
        }

        public double TopSpeed
        {
            get;
            set;
        }

        public double Horsepower
        {
            get;
            set;
        }

Hope this helps

First of I don't feel it's a good idea to use WPF while learning how to program, so I suggest you forget about WPF and start doing some basic console applications. trying to learn WPF while is not a good idea, I know good programmers who have had trouble learning WPF or think they have learned it but really doesn't have any idea of how to utilize WPF. I'm not trying to be a troll, I'm just afraid you're going to choke yourself by trying to learn to much at the same time.

That said I'll go through some of the problems you have in your code.
1)

b.Add((new car()
{
   //don't know how to proceed  
});

What you're trying to do here is using the Object initializer[^]
So you can initialize the properties of your type car, like this:

b.Add((new car()
{
   cylinders = 6.0,
   topspeed = 500.0, // Fast car :P assuming this is kph or mph and not
                     // meters-per-hour :)
   horsepower = 1000.0 
});

2) In Button1_Click you create a new list to which you add a new car with the code we just discussed. But you do not store this list anywhere, what you probably want is to have a field in your class where you can store your car instances.

3) Again in Button1_Click you have this statement

if(i == n)<br />

that statement will never be true as you start you by ensuring i < n in the statement if (i < n)

4) I can go on a bit here, but I'm not even sure you understand what I've just written, and I really don't want to write 2-3 pages here if you can't use i for anything, your question is simply to large. And from the bottom of my heart I highly suggest you do not use WPF untill you have a good crasp of C#.

But if you have a specific question about your code feel free to ask and I'll attempt to explain it for you.

---

Ok, if I understand correctly, your problem is now that you have an instance in window1 which you would like to use in window2.

You can solve this in a couple of ways:
1) You can make the carlist field public and static e.g. public static List<car> carlist = new List<car>();</car></car> when you do that you can access it like so window1.carlist here window1 is not an instance but the type/class name.
This is not a very good solution, fields shouldn't be public and if you have two instances of window1 then they would share the carlist
2) You can give window2 an the instance of window1 you're using, and make the carlist field public or make a property that return the carlist.
3) You can give the carlist to window2 by passing it to the constructor. This is what I would suggest you do.
E.g.

public partial class window1 : Window
{
...
    private void button2_Click(object sender, RoutedEventArgs e)
    {
        window2 win2 = new window2(carlist);
        win2.Show();
    }
...
}

public partial class window2 : Window
{
    private IList<car> carlist;
...
    public window2(IList<car> carlist)
    {
        this.carlist = carlist; // this is the reference to the current instance so
                                // this.carlist refers to the field carlist not the parameter.
        InitializeComponent();
    }
...
}

I think your "fully lubed" in great advice here :), but let me add a few comments, at the risk of oil-pan overflow:

0. what seems 'missing' in the structure of your list is some ID for each Car: what if you have four cars that all have the same identical specs ?

1. replace the TextBoxes used to enter values for Number of Cars, Cylinders, HorsePower, etc., with NumericUpDown controls. (I assume that WPF offers them, or an equivalent ?).

2. consider encapsulating all your business with 'Car' objects in a class (and/or NameSpace as shown here), perhaps like this:

using System.Collections.Generic;

namespace Cars
{
    public class Car
    {
        public double Cylinders{get; set;}

        public double Topspeed{get; set;}

        public double Horsepower{get; set;}
    }

    // we're using inheritance here to make a List<Car>
    public class CarList: List<Car>
    {
        private static int defaultCylinders = 8;
        private static double defaultTopSpeed = 100.0;
        private static double defaultHorsePower = 90.0;

        // we are overloading the Add operator here
        // to allow us to check for the need to set
        // default values, if they are missing ...
        internal void Add(Car newCar)
        {
            if (newCar.Cylinders == 0.0) newCar.Cylinders = defaultCylinders;
            if (newCar.Horsepower == 0.0) newCar.Horsepower = defaultHorsePower;
            if (newCar.Topspeed == 0.0) newCar.Topspeed = defaultTopSpeed;

            // here we call the underlying List<Car> 'Add method
            base.Add(newCar);
        }
    }
}

If there's going to be one-and-only-one List of Cars, you can make the 'CarList class static.

So how would you use this style Class definition to actually make the List: assume this code is in some window or context separate from the (NameSpace of and) definition of the 'Cars' class:

// expose a Public Property containing the CarList built
// in this Window or Context
// so other Windows or Contexts can use it
public Cars.CarList TheCarList { set; get; }

// button press that triggers making the list of cars
private void MakeCarList_Click(object sender, EventArgs e)
{
    // the list of cars to be built
    var ListOCars = new Cars.CarList();

    // 'seed' the exposed public property
    TheCarList = ListOCars;

    int nCars = (int) numericUpDown1.Value;

    for (int i = 0; i < nCars; i++)
    {
        var NewCar = new Cars.Car
        {
            TopSpeed = (double) numericUpDown2.Value,
            Cylinders = (double) numericUpDown3.Value,
            HorsePower = (double) numericUpDown4.Value
        };

        ListOCars.Add(NewCar);
    }
}

The above example uses techniques, syntax (var), and object-initializer syntax, from C#2.0, and later. Tested and verified in WinForms only.