Potential deal with seller finance

[Tanner Bundy]

I just met my neighbors who own a duplex. They confronted me about selling their property by the end of the year. I asked him if they’ve heard about seller finance, they were able to understand the concept so they want 20% down and they’d be willing to set up payments, this would be my first time doing this so I’m just looking for advice for anyone who has done seller-Finance in the past maybe some pointers towards how to set up the note etc. thanks for advice