Betta Fish: New betta owner, this is my good boi Killer.

My roommate got me a beta and some guppies as a birthday present! I love fish a lot but I'm not an experienced betta owner. I want him and my guppies to be happy and healthy. I don't have them yet but I ordered water testing kits, real water plants like duckweed and some greenery.

I would really like help in knowing how to properly care for them going forward. So far they all seem healthy and happy especially with the moss in my tank (they like to nibble).

My betta is very mild as far as personality goes also.