Hang the loaded filament protective case (how to load a filament protective case) on one of the spool holders in the back of your Portrait 3D Printer. The sticker on the silica gel compartment on the filament protective case facing out suggests which side AND extruder to use.
Fit the plastic guide in the center of the protective case into the slot on the spool holder.
Lift the lever on the extruder while feeding the filament until you're unable to feed any more.
Release the Titan lever and go to Setup » Filaments » Load filament on the screen.
Select which extruder and what material you are going to use. Once the Hotend is hot enough, the extruder will start to load filament.