well I finished my pong game using opengl and c++. Is there anywhere I can post it for others to look at?

You can post the code (ideally inline, but in a .zip if you must) here if you are looking for critique on that. If you just want to post it for people to play it or critique the gameplay, try the Your Announcements forum.

well I have finished pong what should my next game be using opengl and c++?

More things moving at the same time, and/or things that make live more difficult for the player.

Here is a list of things you can consider http://www.gamedev.net/page/resources/_/technical/game-programming/your-first-step-to-game-development-starts-here-r2976

It's not the one definitive list though, but it gives a good direction of the kind of games you should consider.

If there is a favorite genre, perhaps you can pick one that has elements of it?

well I have actually finished my pong game I am thinking about developing a space wars/asteroids kind of game.

Sounds good!