Why Wont My internet work?

Heey! Just the other day i bought a new laptop. Once i got it up and running i connected it to the internet. It says that it is connected but it has this odd shaped yellow shape, sorta like a shield or triangle shape with an explamation mark inside (!) on the connection status thing. I can not get the internet to work and i don't no why.. we currently have 4 computers on our wire-less Internet, but i don't think there is a limit.... Please help! (: