Unpack the spool, unravel the knot (if any), cut off the end of the filament with nippers and fix the filament end in side holes of the spool.
Push out the left side door and place the filament spool with the center hole on the holder so that the filament comes out of the spool from the bottom up. Install the side door with the spool in the 3D printer. Insert the filament into the feeder tube.
Use only 68 mm wide spools.
Always hold and fix the filament end while installing and removing the spool into/out of the printer. Prevent filament tangling in the spool: it may cause an abnormal stop during printing and damage the printer.