Download iTunes 7.3 or the latest version. You can find this by going to google and typing in iTunes free download.

Now you need to take you iPhone out and put it in its dock. This should have came with the phone.

The next scree will ask you if you are a new customer and what kind of activation you want. Click everything that corresponds to you.

Next you will be asked if you want to get a new number or transfer an existing number. Note that is you want to transfer numbers, all numbers are not available for transfer.

Next you will have to select and customize you service plan.

You will need to make a iTunes account if you don't already have one. This is a very quick process if you go to the iTunes website. After you make one, you need to sign in.

The next step is to put in all of your personal and billing information.

Read the terms and agreements and check the box. Click next.

You will then be placed on a conformation page. Read over all of the information to make sure everything is correct. If all the info is correct press submit.

That is all there is to it. You have now activated you iPhone.