If you have bad credit the only way you'll get a phone contract cell phone is to get added to a family plan with a family member that has a good enough credit score to apply and get approved for the contract cell phone.
Otherwise you might have to go with a no contract cell phone which you pay for each month upfront with a card or a credit card online.
StraightTalk is a good no contract cell phone provider and they have great coverage and you pay $45.00 per month for unlimited talk, text and web.
You can get the StraightTalk no contract cell phone at Walmart as well as the Prepaid Cell Phone cards as well.