First step is to see if it can detect your wireless router.
Next step would be to connect your computer to the router by ethernet cable and disable wireless security temporarily. While there check that wireless mode matches that of the phone and your computer's wireless adapter -- mixed mode is a safe bet.
Also make sure that Access List (admit/exclude users by MAC ID) in the router is disabled.
See if the phone can then connect, first to the router, then hopefully to the internet.