Using the wifi of samsung star

Hello,

i can't connect my samsung star to the wifi. do i need to setup anything in order to connect? i'm in a free wifi but there's no way i could connect. the prompt is authenthication failed or disconnected. what is an ip address? i check the details of as free wifi and there is no ip address, does it matter to my connection?
pls. enlighten me on this matter.

tnx much!