how can we use data structures in c# ..?

Check this slide show for more info :

Data Structures in C#

http://www.slideshare.net/shahzadsb/data-structure-in-c[^]

An Extensive Examination of Data Structures Using C# : 6 Parts Article series

http://msdn.microsoft.com/en-us/library/ms379570(v=vs.80).aspx[^]

Quick list :

http://stackoverflow.com/questions/128636/net-data-structures-arraylist-list-hashtable-dictionary-sortedlist-sorted[^]

I hope this will help to you.