Starcraft – Why does Starcraft II show no maps in Single Player

The custom game selection will allow you to draw from maps that you have uploaded to battlenet via the Galaxy Editor. As I understand it this is exactly what you want to do and it sounds like you do understand how to publish a map.

I believe there is an option to publish the map privately for custom game use, though I haven't check since Beta.

If you are able to join, it is not due to the restriction of incoming connections.

Three main possibilities:

1. The latency of your network connection is to high (ok, that is what lag means). This might be due to some filters in the university (i.e. they scan for P2P packages) which would increase the latency, or you are playing on servers very far away from you. (other possibilities are also possible of course)
2. Your computer is too slow.
3. The bandwidth provided for each client is not enough to play (ok, this is pretty unlikely)