Riding the surfboard like a pro? (as a thicker girl)

I’ve always tried to get on top, but I honestly don’t understand how this riding thing works. Do I stay on my knees? Do I lean forward? Do I lean back? Do I get on my feet? I don’t like for him to do all the work that’s why I’m trying to figure this thing out. He’s way smaller than me, and I’m not trying to crush him.

it feels like my thighs are taking up all the damn space. So please, any plus size or any girl at this point help me learn how to ride 😭