Before you go the octoprint or other hosted app route, I humbly suggest printing from the SD card while you learn the process engineering to get prints to come out decent. This reduces the number of things you have to learn at once, and the points of failure. The workflow is then simply: (1) acquire or design the model (STL file). (2) slice it (generate .gcode file) and copy to sd card. (3) use the touchscreen to run the gcode file.

You’ll spend most of your fiddling on step 2 since you need to learn what temperatures and speeds work well.