How can I implement files with extension .3ds from 3D Studio MAX to OpenGL (c# or c++).... help mi pleas....

a) There are alot of loaders/tutorials for 3ds files around the net with source code. Most of them are writen using C++ so just take one and convert it to C#.
b) Take a maodel loading lib and write a .net warper around it.
c) Take file specification and write your own loader. This is qite simple becouse 3ds is one of the most documented formats.

ps: If you have question on how to load specific chunks of file please just ask.