Click the arrows, use WASD, or use the arrow keys to make the character move. Remix the project and edit the BF sprite to your character. Copy the costumes from the BF sprite to the BF Trail sprite so it's compatible. You can also edit the Alt animations, but you'll have to copy those costumes to the BF Trail sprite too.
@ssomedude for the BF and BF Trail sprites and costumes. kawaiisprite for the song. Me for the code.