Create a new black solid (New > Solid) and choose to make it the same as the comp size. Drag the solid to the bottom of the layer stack so that it sits behind the dancer.
Add a new yellow solid and position it at the bottom of the layer stack. Draw a rectangular mask over the top two-thirds of the frame and add a feather to the mask by opening the disclosure arrows to reveal the mask properties. To position your dancer on the stage you’ve just created, simply click on her and drag her within the composition window.
There’s a small amount of fringing intermittently throughout the clip around the feet area. You could tidy this up by using a couple of effects in After Effects’ tools, which you’ll learn how to do later.
Duplicate the dancer clip layer by highlighting it and pressing Ctrl/Cmd + D. A second copy of the layer will appear. Turn off the visibility of this layer and drag it beneath the original dancer clip. Add a new solid in a bright colour (we’ve used orange). Drag this beneath the copy dancer layer and set the track matte to use the duplicate dancer layer as a transparency matte.
Although this is working, you can’t readily see the results of your labour yet because the original dancer clip is obscuring the orange silhouette we’ve created. To deal with this issue, and to create the echo effect we’re after, click and drag on the duplicate dancer layer to offset it in time around 0.3 seconds. Experiment to get this completely right on a clip by clip basis.