How work out in pool?

Even if you're out of shape you should be able to - perhaps very slowly - move comfortably between the shallow end and the deep end.

If you are at any time uncomfortable in deep water or unsure of your abilities then it might not be an issue of being in shape. Maybe some swimming lesson refresher courses will help you feel more comfortable and also improve technique in order to improve your stamina. Most public pools offer water aerobics classes that use the noodles (tubes) and such. Maybe that would be a good place to start in addition to just taking walks in your neighborhood.

While swimming is easy on bones and joints it requires much greater stamina than other activities or sports because of the density of the water. Unlike air, it takes a lot of muscle and energy to pull and push yourself through water. It will take time to build that endurance and if you stop swimming regularly you'll lose it quickly. That's one of the main reasons swimmers refuse to take time off when injured.

just swimming around the shallow end of the pool would be good for now. if you want a work out, get some of those weights that you can attach to your arms and legs (like 5 pounds each), and them walk or swim through the pool and you'll be getting quit a workout with just that!