Connectivity issues with new computer

I have wireless internet at my house. I have a new computer, and it is not able to connect to the internet. It shows my wireless provider, which is a small local company called Upward Access, but wont connect...the computer has D-Link adapter installed in it. I am not computer saavy and dont know how to fix this. I think the problem is my router for wireless service is not recognizing this new computer...how can I fix this..in simple terms please!!