i want to join an clan but how do i add tag i cant seem to get it right

Go to Setup - Login, and just type the clan name in before your name, and put brackets round it like so:

[Clan]Username

And then log in.

it creates a new account when i do so

and my fuc*in laptops dont like brackets

First you have to get accepted into the clan.

Then, you can go to the login, and add the [CLAN]before your name.

Or ingame type /login [CLAN]Username password