To access your edited tracks, go to My Creations. My Creations is the last tab at the bottom of the app. Here you can find all the tracks you save from the editor.
Long pressing on a track brings up a menu with options to choose from. Your choices are to delete, add to playlist, favorite, play next, play last, or share.
To edit a track, tap on it, and you will see it start in the player. Tap on the player to slide up the editor from the bottom.
Back in the editor, you can further edit your edited track.