IF you can give us some code, we can be more specific..
tutorials for this question:
http://www.csharp-examples.net/filestream-open-file/
http://www.csharp-examples.net/filestream-read-file/
http://msdn.microsoft.com/en-us/library/system.io.filestream.aspx
http://msdn.microsoft.com/en-us/library/system.io.streamreader%28v=vs.71%29.aspx
hope it will help you..