The younger you start, the better. Kids will try anything, and it's a great way to channel their energy. The reason it is easier for them then you is because they think about it less, and just do it. A child's thought process isn't as thorough as an adults.
Listen to your instructor, and go to a pool on your own(when you feel comfortable) and practice everything you learned.
Remember to keep your face in the water, and breath from the side when you take a stroke. If you pick your head stright up to breath, your stroke will fall apart. Count out a breathing pattern when you take your strokes. Do a 3-1 breathing pattern. 3 strokes then breath. and again, breath to the side under your arm when you take a stroke.
I really admire those older in life then children who do not know how to swim, to start learning. I think everyone in the world should at least know how to swim. weather it's perfect, or just to survive. Knowing how to swim is just as important as knowing how to walk. you never know when you may fall in a pool or off a boat.
Good Luck to you!Answer 2
Firstly, well done you for wanting to learn and doing something about it.
I've taught all ages to swim and not all 4 - 5 yr olds pick it up quickly, some are terrified and a lot don't really listen. For them it is about making them think it is a game not a lesson. You really want to do this and I am sure you will get the hang of it quickly. You will need more than your lesson time if you want to progress quickly, practice all you can between lessons. Do you have a supportive friend who will help and encourage you as well as have fun to build your confidence?
My only other advice is invest in swimming goggles, they really help when you need to have your face in the water.