There are no instructions on how to use the ink converter for the Lamy I got today
Lamy supply some somewhat limited instructions with their bottled ink, but unfortunately not with their converters.
Simply unscrew the barrel and insert the converter as you would a cartridge. Rotate the red end of the converter until the plunger reaches the opening end. Hold your pen in the ink with the nib and black feeder under the surface, rotate the red end in the opposite direction to suck the ink into the converter.
The converter doesn't need to be completely full of ink, but if you seem to be sucking up more air than ink you need to dip your pen deeper into the ink.
Once you have filled you will need some blotting paper or kitchen paper to clean up the nib/grip section. The barrel can be replaced and your pen should be ready to write.