So my iMac wireless doesnt work, If i buy an airport express and set it up with my laptop, can i connect to the internet with the imac through the airport express ethernet port?

If the Mac's WiFi connection is really broken (unlikely) you can add a USB WiFi dongle (search on Amazon or local computer stores) to connect. Make sure the accompanying software is Mac friendly.

did you mean you would like to use the airport express to have a "wired" internet connection? unfortunately, airport express only has one "WAN" port and this is connected to your modem (or another router in the building) that provides the internet connection.

airport express can be used as a router but only on wireless. it mostly acts as an access point.

the "airport extreme" would let you do what you wanna do. ;)