Hair curling products?

I'll just start of by saying my hair is a mess, it's naturally curly underneath, but the top layer of it is straight and it drives me nuts because straighteners never work, but I can't use a curling iron.. (no I mean I literally can't I've been practicing for years and only end up burning my hair or having to make an emergency trip to the salon to the them to pull the damn thing out of my hair)

I've been told to use a gel for curly hair, but I don't know where to begin. So please any product suggestions are appreciated!!