on the menu scroll to print from SD card.
Look for the test print file, and run it.
I don't know the exact name but it may be the only file on the card. Found it - see below -
Everything should work correctly by its self for that file.
When you start using your own files or thingverse files make sure your slicer adds the start and end gcode.
Just search in the forum for the exact directions.
File name is: test-print-hollow.gcode