Nice looking boat, and background scenery (from your driveway?). I assume others will chime in regarding OMC, and Seloc - I have heard, but have no direct experience with either.
General operating instructions for a stern drive boat? I'm sure they're out there. Maybe you can find some videos on launching/retrieving at a boat ramp, or maybe go watch some people do it. Take advantage of the offer from the Previous Owner to go out with you. Take a boating safety course first. Welcome, and wishing you safe and enjoyable boating.