Double click on the timeline to add a new keyframe. Alternatively, to add a keyframe for a desired element, right-click on the timeline and click Add keyframe. Canvas also adds a keyframe automatically on the timeline. After you add a keyframe for an element, if you move the playhead and change the position, rotation, opacity, or size of the element, Canvas adds a keyframe automatically.
When a keyframe is added to the timeline, the application displays a green strip between the starting and ending keyframe. The green strip is the animation.