The IV is unprimed. The V is primed. Both use external ink reservoirs, probably 4 oz, 125 ml.
Ask them for directions. I have gotten both the pre-filled Niagara for my Epson 1280, G Chrome pigment ink, and the unfilled Niagara for my Canon i9900.
What you normally do with an unprimed/unfilled CIS system is:
1. Fill the external ink bottle about 3/4 full.
2. Clamp the feed tube at the external bottle.
3. Pull a vacuum with a pump they supply on the printer outlet end of the cartridge.
4. Unclamp the feed bottle and let the ink fill the cartridge.
A couple of suggestions:
1. Print at least one 8x12 page per week. This keeps the print heads from clogging.
2. If you notice that the Yellow color isn't printing or the ink lines are running dry, try elevating the external ink bottles slightly. I used a 50 sheet paper box. A couple of large solid metal washers might be better to start with.
When a CIS system works well, the cost of ink is low enough that you will end up wall papering your walls, walls of friends, with prints.
When a CIS system acts up, it can be a pain, and leave your fingers quite colourful, to get it working again.