Insert the new filament into the top of the extruder until it stops.

Squeeze the plunger in to feed the new filament into the extruder. Feed it all the way through and in to the hot end.

Once the new filament has reached the hot end, turn the manual feed knob clockwise in order to purge out the previous material. Do this until you see the pure color of the new filament.

You're done!