how to use new sim card in a unlocked iphone

Insert SIM card. Turn phone on. Activate phone.

Are you having a problem of some kind?

Have you restored the phone since you have had it unlocked?

Your tag says iPhone 4. If it's a Verizon 4.. then it doesn't have a sim slot and will only work on Verizon.

Not to mention the fact that a CDMA iPhone 4 can't be unlocked in the first place... 😝