Well first, you have to know what guild to join, you could just randomly join one, but I think it's important to be in a guild with actively speaking players, we have two splinterlands guilds with their own discord channel where we talk in, you're welcome to join if you like you don't have to be a member, Click here to join (if you have Discord of course)
Also, we have a brawl spot open for modern bronze, I will personally guide you with everything you want to know

The guild page can be found in the top left, from where you can search for guilds.

The splinterlands official discord also has a guild recruitment area and you could also ask on X for active players if they have a spot for you.