Hi Andi, this article will show you how - https://www.todayshomeowner.com/painting-wood-floors/
I have many painted floors and they were fairly easy to do. Make sure floor is clean as possible, any repairs made. Use a good oil (if possible . . . for me I can no longer use oil paint inside) deck/patio paint. Even the checker board floor here was not that difficult. . . I just drew lines and followed them. . . no paint tape! The floor with doors is linoleum. The first green floor is pine attic floor, the second green is maple wood and the checkerboard is oak. Paint works great on all.
Be sure to use latex enamel - the best you can afford so that it will stand up to walking and scrubbing. Also consider polyurethane to prevent ships and wear.
I've done this. I used paint specifically intended for floors and before applying, cleaned the floor to remove any wax or dirt using a TSP substitute. I even scrubbed out the corners and along the wall baseboard with a brush. Once it was completely dry, I applied the paint with a roller on an extension pole. Be sure to tape and cover anything you don't want to get the paint on.