You need to buy a dripping atomizer with 510 threads. You can buy them from all over the place online. There are all different types. You can use the atomizer on your current e-cig setup. I don't know what your setup is but I will go ahead and assume it a 3.7 volt unit. As long as you are using a 3.7 volt unit you can use a normal resistance or low resistance atomizer. (low resistance will burn hotter and create more vapor). Some atomizers have a small wick inside to help direct juice to the hot coils, this can be a problem because the wick can get burnt and produce a terrible taste. Other atomizers are "wickless", you have to make sure you keep the coils wet. Dripping can produce the best flavor but you have to keep putting a few drips of liquid in the atomizer every few puffs.
Assuming you are using a 3.7 volt device....I suggest you get this---
510 LR Atomizers
I buy a lot from them, very trustworthy, and will happily answer the phone and discuss everything with you.
What e-cig are you using?