The Timeline is your best friend in Flash. Everything is done in frames, like a movie. Each frame can have different layers, like Photoshop. Each frame can be any size you want. That's pretty much it. Flash is really straight forward.
Its a photoshop site but it has a section in the forums dedicated to flash, a member there Lillemartin is really good with flash he can help if you have questions.
Use the tutorials in the flash program. They are first rate, and will teach you the basics really quickly. They are interactive, so they show you waht to do.
Definately work through the tutorials! They will take you though all the controls, and step by step, creation of a example project. Take your time and work through it, the reward is great!
