What are the steps to set up cellular data?

Just bought an unlocked iPhone. I want to get AT&T 4G LTE service, but how do I go about doing that? I'm not very good at computers.

Just go to the ATT Wireless website and follow the instructions to sign up for new service. There will be an option somewhere for buying anew phone or bringing your own. Sometimes that "bring your own device" option is a little hard to find as they tend to like to sell you a phone.

You will need the phone IMSI and probably SN (possibly other numbers). These should all be on the box, but it is also better to go into the phone setting and get the information there (if you bought this online or something the phone may not match the box). If you can't find it, just google "find the IMSI on {whatever phone you have}"

You should be able to do everything online.

If it is proving difficult, simply take it to an ATT store and have them set up your account for you.

A computer isn't involved. It should just be a matter of putting in the APN in the cellular data section on the phone. In most cases its already set up though, but on the off chance it isn't…