"Hmm... First, you need to prove yourself. Go outside of town and capture your 1st monster! The forest west of here would be a good place. You only get once chance per monster, so you need to lower its health in order to better your chances."
How to Complete
To complete this quest, leave the town and walk to the forest west of the town. You will immediately enter a fight. You will need to tap the card next to the monster's name to capture it, but you should weaken the monster as much as possible first.