Hey IBeGood
if you head to /warp commands there should be a section for Clan Commands,
examples:
-/clan upgrade tag : ingame TagName used in chat usually in the form of [CLAN]
-/clan upgrade color1 or color2 : ingame TagColor for brackets or letters within brackets
Now with clans, they will deduct money from your clan balance every 8 hours which you need to add with /clan pay (Amount) if you do not keep up with the tax your clan will be disbanded and you will have to pay again to create it, the amount of tax will depend on how many members you have within your clan so don't try to add too many slots in when you don't need them and make sure you are genuinely ready to keep up with the price of running a clan. There's a different tier system that determines what gyms you can go for which have different rules for the pokemon you can use, so some will allow Legends and the others won't. The competition for gyms are quite skilled so I recommend you have a good team and two other officers with similarly great teams
Hopefully, this helps, if you have any more questions let us know or catch us at:
https://discord.gg/YUhkuy6a
Take care now
-ComplexHand