I have a 18 by 33 oval above ground pool the name is Blossom. All my rails are rusting and the rail that holds the liner. What can I do?

Water with chlorine in it does nasty things to metal. I would suggest talking to someone who supports spa's, hot tubs, and pools etc. If I were doing it on the cheap I would find a paint or coating that could withstand the chorine in the air, but it can attack from the inside out on hollow tubing etc. so that would be a short term solution. Some metals are more reactive to the chorine. It might be that you can find a man made product that is strong enough and capable of dealing with the chlorine. We installed a hot tub for a guy I knew years ago. He built an enclosed room around the hot tub. The vent fans and lights and other metal things didn't hold up very well. The redwood decking and walls and ceiling seem to fair much better. Some types of stainless tubing and support braces would probably do well, but expensive. This isn't a new problem by any means, so the good spa-pool people should be aware of solutions.

MY recommendation... is taking those parts to a professional to have them media blasted and powder coated. That is the longest lasting option you have available.