So lets say..

that I find a house I want to buy from a FSBO…I convince them to do seller financing. Then what do I do? Would I need to see an attorney to write the contract? I would have no idea how to do it myself.

You need to have a contract that you use and are familiar with. Steve Cook gives one away on his site Once you have a signed contract take it to a local title company or RE attorney. You need a profesional to handle the closing.