What is an equal power crossfade?
An equal-power crossfade is recommended for material that isn't phase-coherent as, in a crossfade between two different types of material, it will mean that the overall volume will be maintained through the crossfade.
How to use crossfade?
Turn on the Smart Tool by pressing F6+F7. Move the mouse close to a region boundary and toward the bottom of the track. The icon changes into a symbol that looks like a crossfade. Click and drag the cursor either to the left or to the right, and a crossfade will form, centered on the boundary.