Literally just fucking swim. You won't get better at swimming unless you swim and kind of just figure it out for yourself. If you want to get professionally good at it then yeah a trainer will help after you've been swimming for a bit, but otherwise the whole goal is to just work muscle groups and burn calories.
I suggest breaststroke as it's the most efficient for supplementing chest/shoulder work. Freestyle ("front crawl") is also an option as is backstroke. Ignore faggots who shill butterfly or scissor stroking. Scissor stroke is fucking autistic as shit and I don't know why it's even a thing, and butterfly stroke is just an autistic version of breaststroke. Literally all you need to learn is breaststroke and backstroke. Breaststroke will be your main stroke for gaining depth and for propelling forward (keep your head level with your back underwater instead of doing it from the surface, faggot), backstroke will be your survival stroke in case you're ever stranded in open water because it uses the least amount of energy of any stroke. Freestyle is just for cardio purposes because you can go really fast and splash the dumb bitches who are playing in the pool. Also use breaststroke to stay underwater so you can watch the qt wearing a skimpy bikini when she jumps around in the water being an idiot. Underwater bouncing titties are great.