Building takes a long time. Look for open guilds here:

https://splinterlands.com/guilds

Most guilds will need you to contribute in both DEC (called Guild Points/GP) and guild battles (called brawls). Best start out in a guild that is quite low, learn how everything works, and then you can decide if you want to apply in a bigger guild.

You can also look around and see if you can find small guilds that are attached to bigger ones. I think Fallen Angels have a few branches, same for the Pizza guilds - there you can find a lot of support as well.