You've got the eGo Mega cartomizers. I used a couple of those and filled them by dripping juice into the hole in the battery connection end. Mine held around 60 drops of liquid when new and about 35 on a refill. Try slowly dripping about 40 drops into it, then blow through the mouthpiece with a paper towel or napkin to catch any excess. If you don't blow any out try dripping another 10 drops or so. Repeat until you hear a slight gurgling sound when you blow through it. If you over fill it just blow out the extra.
What he said lol