Even the three-piece units (Joye 510, for instance) can be 2-piece units by simply changing out the atty/cart for a cartomizer. That one you have looks like 510 threading to me. I'd take the batteries down to the local smoke shop and ask if they have cartomizers to fit it. While you are there, buy some small bottles of juice. Even if yours come pre-filled with flavor, you can re-fill them with juice you buy and not have to buy their expensive (pre-filled) replacements. That will save some money. Most of us started out where you are...I bought my first e-cig from a mall kiosk...and paid too much for it. But it was a learning experience, and I passed it along to my sister after I got a better system. We all have to start somewhere. Good luck.
EDIT: DON'T buy their replacement cartomizers.....and if you signed up for some sort of a recurring charge for them, get out of it. Their price is high, high. Like I said, you can 1)find them cheaper, and 2) re-fill the ones you have....just buy some juice.
Just start reading around the forums here and you will absolutely learn, learn, learn...
I went to their site, and it still looks like a 510 connection to me.