I'm assuming you are referring to a a land contract where the seller basically holds the mortgage on the property and collects principal, interest, taxes and insurance much like a bank. These typically are at least 10% down and somewhat higher interest rate. If you default on your payments, the seller will foreclose.
There are minimal properties for sale offering the possibility of a land contract. These can be found occasionally on the local multiple listing service. You could also check For Sale by Owner and other private listings.
First, you need to find a reliable realtor. They may also be able to represent you as a Buyer's Agent with FSBOs or private sales.