I Love Fishing

What am I doing wrong? I love to fish this one way my dad showed me. I use a fly with a spinning rod instead of a fly rod. My problem is that my rigging keeps twisting up. I don't remember it ever doing this when my dad would do it for me. I use a clear bobber with a swivel, about 3 ft leader line, and my fly. Maybe I'm casting wrong or something. I got new line. The fly and the leader line twist all around and up past the bobber. So when I reel it in my fly doesn't skim on top of the water correctly or back far enough from the bobber.