Can you float on your back?  Just float for a little bit and relax and enjoy the feeling of "flying" in the water.  It takes no effort to do this and you with continuously breathe with your face being out of the water. In the shallow end, hold your breath and blow out all of your air and then sit on the pool floor.  If you can only hold your breath for a couple of seconds that's ok, when you need to breathe, just stand up.  Keep doing this and get comfortable being under water, knowing you can just stand up.  When comfortable, do the same thing in the deep end.  Go slowly and just have fun.