Sex help! Riding 101 lady's I need your tips!

So its been quiet a while since ive riden a guy. And me and my boyfriend have been having sex lately and he wants me to ride him he doesn't push it but when I tried I just like forgot how to position my self I guess. This is kind of detailed so bare with me. My beds squeaky so let's just say can't do it on there. But he gets on the floor and I try to ride him but I have trouble getting it in I get kind of tenser I guess no matter how wet I am. And he's also kind of on the smaller size with a tummy and I'm 5'4 with short legs and I just can't Idk position my feet correctly. Like do you put your feet positioned in the inner thigh part or kind of like sit. And do you move your hips or literally go up and down. I've seen and been with guys who prefer both but I'm not sure how to position my legs when doing either moves. And is it best for him to sit down or lie?