Creating a Composition
Start by choosing “Add Composition” on the Media menu. Give the composition a name, and type a suitable size into the “Reference Frame” field. In this case, it is a good idea to make the reference frame just slightly larger than the still image frame around the video. This reference frame will be used later when manipulating the composition as a whole from the main timeline.
Open the composition’s timeline window by double-clicking the newly added composition item in the Media window. Notice that the content of the Stage window changes when the composition window appears. Instead of showing the display rectangles, it now shows the reference frame of the composition. While editing a composition, its preview appears in the Stage window, temporarily replacing the preview of the displays. To restore the Stage window to its usual state, select the main timeline window.
To change the size of the reference frame, or any other composition setting, choose “Timeline Settings” on the Timeline menu while the composition’s window is active.