Playlist
The session playlist area is located at the bottom of the Performance screen. It is divided into two areas - sections on the left and tempos on the right.
Sections
When you click on each section, the tempo choices will update to reflect what options are available for the selected section. You can change tempo for each section by clicking on the tempo number, the app will remember your choice during the session.
This is probably the best way to figure out which tempos will work for your particular performance - just try them out and see what works best for you.
Auto-continue Mode
Every section button with an arrow on the right side, like this:
means that this section has an auto-continue mode enabled. When you start such sections, the app will automatically continue to the next one - no pedal pressing is needed.
This mode greatly simplifies the whole process as all adjacent sections (back to back with no gaps) will be played automatically.
You can still be in full manual control of the performance by disabling the auto-continue mode for the session by clicking the switch at the bottom.