counting specific character in a string using Asp.Net

// given the following, and assuming you don't care about case-sensitivity:
string myString = "Download";
char myChar = 'o';
int count = 0;

// if case-sensitivity matters, comment these two lines
myChar = myChar.ToLower();
myString = myString.ToLower()

// do this:
foreach (char c in myString)
{
    count += (c = myChar) ? 1 : 0;
}

// or this:
count = myString.Count(ch => ch == myChar);

// or this:
int count = (from c in myString
             where c == myChar
             select c).Count();

Dim s As String = "How are you doing?"
Dim Count As Integer = (From c As Char In s.ToCharArray Where c.Equals("o"c) Select c).Count

Public Function CountChar(ByVal str As String, ByVal Ch1 As Char) As Integer
  Dim iCnt As Integer = 0
  For Each c As Char In str
     If c = Ch1 Then iCnt += 1
 Next
CountChar = iCnt
End Function