How to go from contract to pay as you go?

I'm on Vodafone and the contract has just ended so I have brought a Vodafone pay as you go sim. How do I put my sim in? Not literally, I mean, do I need to wipe the phone? Do i get it unlocked? How do i clear current Vodafone settings from it? How do I go about it? I just want my new pay as you go sim to work in my current iPhone 4.

Phone vodaphoe and ask for help i did this and still kept my contract number x

Put the prepaid SIM card into your phone, and restart it. If it asks for a network unlock code then you will need to contact your carrier and request your subsidy unlock code to use their pay as you go network. If your contract remains right now, you better have paid your bills and have everything altogether because depending on the carrier they might withhold your subsidy unlock code for the smallest of reasons. Sometimes lots of RED TAPE. Also because you have an i Phones you may have a serious problem with keeping your data for I know that certain i Phones wipe everything to factory state with the network unlock code. If your able to get past all these obstacles or just surpass them all together then your iPhone will work with they're pay as you go network. Just be wary that incompatibilities may be caused in network frequency because sometimes carriers have separate spectrum for they're prepaid or pay as you go networks. MOST DON'T so it will probably work.