if you scroll left to the F trim table
press Edit up in the top right corner
press Modify Table
the table moves to edit mode
Click on the cell you want to change (or click-hold-drag across many cells)
Slide finger up the screen to raise the % trim, or slide down to lower it
When finished that trim adjustment, press the green tick button
If you want to change more trims, do. If not, and you are finished for now, press the green tick again
If you load that map to the ECU and run it, it will use the trims. Doing it this way means you can keep track of how much you changed the original fuel tables.
However if you want to commit the trims to the fuel tables, click Edit again and then click Apply Trims (ensure F trim global is ticked so it applies to all F tables)
If you want to modify the L tables (for low throttle positions like 0-6% iirc) i think you have to modify the L tables themselves, using same editing technique as above.
Save and download the map