Shame on your "professional" installer for not demonstrating the installation and removal techniques. If you haven't figured it out yet, to remove the rings, position the tool over the bolt with the longer extension on the pool side. Twist the tool, allowing the extension to come between the ring and the bolt. This should allow the ring to pop off.

Installing is straight forward, but I was surprised at the force required. Place the tool through the ring and over the bolt. Have the ring about a foot up the tool. Place your foot over spring/plastic cover and pull away from the pool while maintaining foot pressure. Step down to slide ring to the surface and over the bolt.

Fold the cover using the Z-fold technique.

Lubing would be a good idea, but I don't think it's required every year. This is my 4th year with no lube and all bolts easily screw in/out. I do hose them off with a forceful stream to remove any dirt/particles before screwing them in, though.