I believe ATT U-Verse is DSL which means you have to log into your modem (is it an all in one modem / router?) If so, it is generally 192.168.0.1 or 192.168.1.1 and setup the connection.
If my memory serves me correctly you will have to change the connection type to PPPoE, Dynamic IP, and put in your att credentials.
It would be easier to just get ATT on the phone and have them walk you through it, since they have all the info you need in front of them.