Express Action Sports

I am an amateur photographer and have started selling my digital photos, after years of family and friends telling me I should! Mostly Action Sports pics. Now several people have asked to buy the "digital images" from me. I mean basically they will be able to order and or print their own pics, defeating the purpose of me coming to the event and photographing them. Don’t get me wrong, I never buy from photographers either! I always have taken my own pics of my kids/family. I bring my camera everywhere. But the thing is, I was there with my camera and took the pic. How much should I sell them for? I mean if they don’t buy the prints, then what would I do with them anyway? But then again, if I just give them away, what am I doing this for?
I’m sorry, I really didn’t make that clear. It is the person/s who are in the picture that want to purchase it. I get invited to sporting events, usually by the coaches or parents, I photograph the games and am trying to sell the pics to the parents.
Also, what makes any pic I take copyrighted? Do I have to do anything?

Obviously I am new at this (lol) and appreciate any advice! Thanks!

I don’t really understand who is wanting to buy your image.

You need to understand about copyright law in this circumstance. Will you be selling the copyright to this person, which means they will own the image?