L 'n' D,
As it sounds like you may use the Starbucks wi-fi, I'll try to recount how I got signed up. At least it will give you an idea where to start.
I never would have figured it out, but I was at a new Sbucks, and an employee there was eager to help me. It just so happened that I was on an "egg" shopping trip.
Let's see, I think I had to start by purchasing a Starbucks card (just basically cash that you store for use at Sbucks).
Then I went online and... somewhere... signed up for an AT&T wi-fi account (this stage is fuzzy, sorry).
Then I think I also had to sign up on Starbucks' site, making a log-in and password (or maybe this was before or instead of the last step), I then went over to the left-hand menu on the Sbucks site, and looked under something like "benefits" and found the way to link the AT&T account with an Sbucks name and password (gee, sorry this is so vague).
But now it's simple. I just keep a bit of money on the card, and use it every so often. When I go into Sbucks I just open my laptop and try to go to a website, and then the Starbucks/AT&T wi-fi page comes up. I type in my ID and password, and select "AT&T" wi-fi from a drop down box, and I'm in.
I think I've even gone over two hours a time or two and not been cut off. I usually buy something when I'm there, in repayment, but I have pulled into the parking lot a time or two just to check something like gasbuddy.com (but then again I've spent quite a bit in Sbucks at other times without going online).