Wifi not working properly

Ok, so im in college and as of right now I am connected to the internet through an ethernet cable. The problem is that my school offers Wifi, but for  some reason when i try to connect to a network the "connect to a network" window disapears and does not connect to the internet. I have a dell xps m1530 and an intel wifi card. I got this laptop only a few months ago. THe wierd thing is that the laptop can automatically connect to my wireless network back home, but nothing elses :/ . Please help, this is really frustrating