Ip in games

I connect to the internet trough a adsl modem. My adsl modem is connected to a hub and the hub is connected to my computers.

For example: When i have started a tetrinet(some kinda tetris game for online play)server i can't let other users connect to my computer. The ip i got assigned from my internet provider connects to the adsl modem, but not to my computer, what can i do about it?
Please help???

You cannot host online games if you are not the host of your Network.

How can i become the host of my network??

You'd have to connect the hub to the computer you'd want to  act as the host of your network.

I donot know much more about HUB's, I used to own one, but not being able to host never bugged me so I never looked into it.