I'm no mechanic either.
Small engine oil change should be pretty straight forward.
Google it, brand and model engine.
Check your manual again. 20 may have been the page number. Just kidding.
NSMaple 1 is right about draining.
First thing I do...is tuck my beard in. Then I pull my engines, put them on the bench, clean, and change oil. It's a bit of work and probably not necessary but a clean engine looks like I care, and cools better. The conveyor engine is in a hard to get at spot, huge mess, so I just split the Love Joy coupling and pull them off so I can tip them to drain and fill. I'll be doing that today. Did the SuperSplit yesterday. A few bolts and it's on the bench. Actually not. It was outside on a cart, as the wood stove was going and the engine has fuel in it.
Neither take much oil, less than a quart, so I change frequently.
I never know if you push the stick in to check oil level, or push it in and screw it in to check, so I do the first figuring there is more oil and if it is too much it will blow it out the case breather, if and where there is one. Hasn't happened yet.
Did I say, I'm no mechanic.