I think you need a harness for them that connects the cartridge to the various ports on the machine in order to get most use out of it. IIRC he sells the manual separately and it seems expensive for what I assume is a photocopy.
See here for a manual (not necessarily for the carts linked to above): http://www.commodore128.org/index.php?action=downloads;sa=downfile&id=305
See here for a manual (not necessarily for the carts linked to above): http://www.commodore128.org/index.php?action=downloads;sa=downfile&id=305

