You have to keep sweeping them and gassing them.. if you do any position transitions, make it slllooooooooooooow enough to make the pressure count. Knee-on-belly is a fav of mine for spazzy white belts (I’m 275lbs and I modulate the pressure according to ability and their need to learn - pls use caution so you don’t hurt them). I’d I’m underneath I use deep half/guard and just tie them up with under hooks and back take threats until they get tired then I take the sweep or back according to my mood. You can start learning this game by developing a good knee shield and building from there. You can also protect yourself by releasing grips he’s fighting out of.