hey guys help me with this please

I just bought a Linkysys Wireless G router 2.4ghz.I ran the cd and followed all the instructions it told me to do and did all of the them.I got all the way to the end and it started to connect then popped up up and said power off your modem and try again. I did this a few times still nothing.Im not sure what else to do.The modem im using is verizon dsl modem.Im trying to run it wireless to my desktop upstairs. Just tryed it again and got it hooked up and got to the part where yout type admin and all that but stil dont know what to do.After i got there and closed that out i still cant connect to the internet on my main computer. If you know please tell me and dont read it and not reply.

Thank You