First time on a motorway?

i ped my test in june this year and have just about got my confidence as i have bad nerves. I never got taught anything about motorways and reading up on them has made me very wary because everyone talks about then with dread, so i just wondered what the big deal is? How are you supposed to join and leave a motorway? I hope i dont sound stupid but i never honestly learnt anything about it and feel scared to just drive without any basic knowledge? thank you... also what was your first time on the motorway like?