That is an Evod style clearomizer. The metal just above your thumb (tank base) unscrews from the battery... then that same piece unscrews from the blue part (tank). You put the eliquid in the blue part up to the top of the center tube. Then screw the base back on, then screw back onto the battery.
When the battery goes dead, you'll unscrew the whole tank at the metal base, screw the battery onto the charger... charge until green. Then put it back together and repeat.
You'll need to get EVOD coils and replace it about once every 1-2 weeks depending on how much you vape.