How to activate my new (to me) Iphone 4S?

Okay, I have an Iphone 3gs. I just got an Iphone 4s in the mail today. All I need to know is how to get rid of the "no service" text at the top of the screen. That is all I need to know. I have looked everywhere, and am starting to get frustrated. I have even called on my 3gs, that didn't do anything at all since the pre programmed voice thought it was activated (I believe it was thinking that I wanted to activate my 3gs). Its not like I can call on my 4s since I need service. What is an easy and quick way to get everything working the way a normal Iphone would work.

Oh and if anyone knows how to get all your old pictures (without using Icloud) off my 3gs to my 4s, that would be great, but it is not top priority at this moment in life. Thanks.

Added (1). That is one problem I forgot to mention, I got rid of my landline because all of those stupid telemarketers. I will definitely take it to my local AT&T store. I just want to see if there's anything I can do before I make the effort to go there. I hate talking over the phone too, to one of those reps or whatever because I can hardly understand them one bit.

You can call your provider from a land line and ask them to move your service to the new phone. They will ask you questions about the new phone to be sure it's unlocked. If all is good, they will transfer your old number to the new phone and you will be good to go. You can go into your providers store as that might be quicker also