I don't know how to work my photography camera?

I'm taking a photography class this year and a family friend let me use his Nikomat camera (lends is a NIKKOR-H) and once I put my film in, the lends is black and it won't take pictures. Any ideas on what the problem is.

You didn't say which Nikkormat you have, but you can find the manuals for most of the Nikkormat series at the website I've linked.

Old, manual cameras are harder to use. They let you make mistakes so you need to know what the settings do before you start taking photos. Read through the manual with the camera in front of you, no film in it. Once you're happy that you understand the controls, then load a film and have another go.

I agree, you can delete a picture you have taken on film and you will get only so many shots before you have to change the film so make sure you understand the camera well before you start snapping.