I am unable to configure my 2007 macbook3.1 with the internet

I am not able to configure my 2007 macbook 3.1 with my internet service. I took the macbook into the genius bar yesterday for a different problem and the tech updated everything and told me to take it home and try it to see if everything was OK. When I attempted to do that, I was unable to get on the internet. First I called my internet provider, Centurylink, but they told me that since it was an apple product, they were limited in what they could do and they gave me the applecare number. I called the applecare number to see if apple could help Applecare suggested I try the two free options that could help me fix the problem. The first was to follow instructions outlined in an e mail that they sent me. Did not work. Now I am trying to get community help. I might mention that when I turned the computer on after returning home from the genius bar, the connection diagnostic tool was trying to fix the problem. I proceeded to redo all the steps several times, but could not get it to work. Apple said my only remaining options if you are unable to help is to take it back to the genius bar or pay the one time $29 fee. I'm not unwilling to pay, but since I was able to connect before I took it in, it doesn't seem ethical that I should have to pay to get this problem corrected. Anyway, here is

some additional info you may need:

Processor intel Core Z Duo

Processor speed 2.2 GHz

Memory 3 GB

I sure hope someone can help me get this problem corrected.

Bev