You can add keyframes to a channel's animation curve. Added points are unlocked and appear as square outlines on the curve. Adding a keyframe to the animation curve does not add a vertex to a motion path. See Modifying Motion Path Speed for details about using Add mode with motion paths.

To add a keyframe:

1. Select the channel.
2. From the Edit Mode box, select Add (or press spacebar+A).
3. Position the cursor at the coordinates (frame number and value) where you want to add the keyframe and click.

   The keyframe is added at the specified coordinates for all selected channels. You can also move the new keyframe after it is added. In the Animation Curve window, the shape of the animation curve and the slope of the new keyframe are generated automatically.