Press S to open the Scale parameter, click on the chain to unlink the proportions, hold down Shift and scrub on the X parameter to the right, until it covers the composition edge to edge.Select the Layer Solid in the Timeline and select Effect > Generate > Checkerboard from the main menu.In the Solid Settings dialog box, click the Make Comp Size button, change the Width to 20, and choose any color from the color box below and click OK.From the main menu, choose Layer > New Solid.To create a background filled with animated stripes:.These effects need to be applied to a layer and are typically applied to a layer solid or an adjustment layer. You can create seemingly complex animated elements from scratch using Generate effects.
What you learned: Create an animated background using a Generate effect