What is the first level in dog agility and what is the title you want to try to get?

I ordered the book "All About Agility" that should answer all my questions but it'll take a few weeks for it to come. I know there are different agility organizations like AKC and UKC? Which is the most popular? What is the very first level you enter and what is expected of your dog? My dog is just completing an 8 week course so she has a ways to go. She is awesome at everything and fast but scared of the teeter totter and the dog walk if it's too high (which I understand takes a while for dogs to get used to). I want to start teaching her weaving which I know she'll excel at and not worry so much about the teeter totter and dog walk yet. My instructor wants all dogs to repeat the beginner course if they can't do all the equipment but this frustrates me because she can run the course perfectly if it was just the A frame, hurdles, all tunnels, table, and tire jump. She is a Sheltie. She already has her CD obedience title and is barely a year old. There is an agility (cont'd)