My grandma gave me an iphone, can I buy a sim card for it?

I got a free iphone for my birthday, but my phones sim card won't fit in it. I already have an at&t plan and the phone is an at&t phone. Can I get a sim card for it, and will it be easy to transfer my account over?

The thing with iphones is that it is very difficult to transfer data over from a non iphone such as an android. What I would do is let your phone company know you got a new phone, and have them put the new phone on the plan. You might be able to keep your number, if at&t permits. As for transferring the data, if you can, save all of your pictures, etc, on your computer and then once your iphone is up and working, get itunes, and have itunes sync your phone with your computer. You can get the pictures, songs, etc that were saved on your computer from there. Contacts can be imported directly from your phone to the iphone.