Xbox360 help! I need help with xbox live!?

ok i need major help from an xbox expert!!! plz......

i have connected to xbox live (gold membership) i can add friends.

But i am unable to join chats and i cant play multiplayer online wat is going on?

i rang xbox and they told me to change port numbers but i dont no how to do that......plz help....i realy want 2 start playin....tell me if u need more onfo .......my router is ZyXELXbox360 help! I need help with xbox live!?
Alright, I think we're going to need a bit more information. What happens when you try to join chats or games? Are you completely unable to join them or do you just get booted when you try to join them? Also, what speed connection do you have? If you're running DSL or some connection around the 1.5 mbps speed, you're connection may be to slow or laggy for Xbox Live. If you've got Cable through Comcast or something similar it's probably not your connection.

Hope I can help!