To start,

File new. For the most part the defualts will do. You will Want, these settings. Mode 2D or 3D depends on what you want to do. Some functions only work in 3d. what i do is start with 3d and if i need a function that needs 3d I just change it. All of these settings can be changed later if need be. If your working on a complicated scene it would be a good idea to name your layers.

Be aware of your footage, this goes for any editing or compositing program. I often find that students do not know what aspect ratio, frame rate or field order there footage is in.

Layer notes.

When you first start you will have a single node. Right click on it, import footage. (L is the keyboard shortcut for organizing layouts) For this example i have imported a clip of robo spinning.

This is the bare bones of every workspace. The top node is the footage. This will bring up footage related options such as aspect ratio, duration, frame rate of the footage, alpha and so forth. Note the tiny icon bottom left. This indicates if the footage is a still or sequence.

the second circle node is for transforms. rotation scale postision. you can also change the output rez and other settings. The type of layer can also be changed. (from normal to overlay or whatever)

The third node is the composit layer. From here you can adjust the final output options. Frame rate and rez at the render. The frame duration of the workspace,

To add aditional footage, right click on the composit layer, import footage. New footage will always be placed on top. you can go into the workspace panel to change the order.

You can click on the lines with arrows to change the connections. the red bar at the bottom of any thumbnail can be clicked on then dragged to make a new arrow and connection.