Basically the first thing you want to do is drain the water off of your pool cover. Good luck getting it off if you don’t. Once that is done, you’ll want to remove it and let it dry. No one wants to put a pool cover away wet! Hang it over a swingset or some chairs or simply lay it out on the driveway or on the grass, whatever works best for you.
Now you are left with some water in the pool and likely some leaves and other debris too. Get all of that out and refill the pool to its proper depth. This will allow you to use the vacuum later on. Before the water rises too high, get those pipes and fittings back in, you don’t want the water pouring out of those holes!
Reconnect your pump and filter, which should still be clean since you would have put it away clean in the fall, right? Once all is well with the water level, it’s time to wipe down the walls, vacuum up all the left over debris and make the water great to swim in. This usually involves a dose of shock, a highly concentrated chlorine product that will eliminate all the bugs and bacteria and leave your water sparkling and clean.
Now is a great time to get your water tested and to put the right chemicals in to get a balanced and healthy water. pH is an important thing, if it’s off by just a little bit it can mean an uncomfortable swim for your family. If in doubt, or the job just seems way to much to do alone there are companies that specialize in opening and closing pools so you don’t have the added work and fuss.