A complete answer would depend on what type of projection you wish to accomplish. There are various type of projections including orthogonal (which will not give you a sense of distance, but which is easiest to implement) and various angular algorithms. One start would be to check out

http://www.gamedev.net/reference/list.asp?categoryid=40

but there are many resources available if you search the internet. This site has a few articles on using OpenGL as well.