Congratulations ... and welcome to our world!
By the time you read this answer, you probably will already have refilled them. They don't have a large capacity. Prefilled cartridges are just a gentle way to get started in
vaping. From now on, you'll want to fill your own (with
good e-liquid) ... or
drip that
e-liquid directly on the atomizer.
This page of my
Wonderful World of Vaping V2 shows you (primarily using others' videos, especially Doctor Vapor's) how to do that filling or dripping ... and
this article lists some of the places to order really good e-liquid from.
Enjoy the adventure that awaits!