Hello there !
In order to tame a pet you need a respective skill (all of them can be acquired at level 1 and are worth of 3 other abilities):
Please keep in mind that not all beasts/demons can be tamed. According to my knowledge all dragons / undeads are tamable.
Quick guide with screenshots:
For this one we will be using tame beast (hunter ability):
first of all, let's roll the ability from cards
we will need to find a tamable beast that is the same or lower level than our character
Start channeling your Tame Beast ability (this is channeled ability so NPC's with stuns / interrupts / knockbacks can interrupt your cast).
Enjoy your new friend !
If you have any questions call me in game : Peacefullnpc (alar server)