I am probably not the best one to respond, as I tend not to use the multi-part songs for much. For me, it just requires too much concentration on when to hit the pedal rather than playing along. That said, the songs are generally set up with an intro, multiple “main parts,” transitions, and an outro/ending. There is an accent hit available. When you start a song, it goes through the intro and right into the first main loop. It will stay in the main loop until you tell it to move on, by tapping the pedal, or by holding the pedal which activates a transition and then moves to the next main loop. Why do this? Maybe you like verse 1 and want to jam over it. Likewise with the other main parts. It is designed to give you flexibility in how you perform the song, and not lock you into a copy of the original arrangement. If you want to play just like the original, you can do that by tapping or holding at the right times. When you get through the main loops, they will loop back to the first main loop, unless you tell the pedal to go to the ending. Oh, and to get to the ending, you have to double tap the pedal.
You can do some song editing with Beat Buddy Manager, but really, it just lets you build from already constructed song sections. To really create songs, you need some kind of DAW, digital audio workstation, such as Logic, Cubase, ProTools, Audacity, MixPad, to name a few. Then you can create Midi parts and import them into Beat Buddy Manager and then into the pedal. Look on our Resources section here on the forum. We have something over 1500 songs already created. You can get those into your Beat Buddy using file>import>song in the Beat Buddy Manager. Then take a look to see how those are structured. It might give you some other ideas or a better understanding.