If i placed a item for sale i.e.';sony ps3 for sale 700'; and someone purchased it with a credit card how do i ?

I'm assuming you mean someone WANTS to purchase it with it a credit card and need to know how to accept a credit card payment? Pay pal allows individuals to accept credit card payments, however there are risks and the credit card holder could do a charge back and you could be in debt to pay pal for the money. Read the user agreements completely before you agree to this. For private sales, nothing is as good as cash for the seller.