Sorry, your question is too vague. Tell us a bit about what you know, what experience you have, what you are currently learning and mostly anything that you have specific questions about or problems with.
Heels down, eyes up (and head up), sit up tall shoulders back, keep a bend in your elbow and your hands low. And relax!
I'm not really sure how to answer your question, but that's about as basic as it can get. There's a lot to know about riding and your question is very vague. Even the elaboration on the original question is vague.
Do you want to know how to get a horse ready to ride (grooming and tacking up)? Do you need to know how to get on a horse or get them to stand still to get on them (mount them)? Do you want to know how to get the horse to move forward and back up? Steering? Slowing down? How to jump? We need more info in order to answer your question properly.