So i need help to change my Steam account to gaijin and i dont know how i have done anything and nothing happend
I do not think you can change the account that way, the only think you can do (or possibly could do, it might have been changed to not be available anymore) is link an email to the Steam account.
But completely changing the account from Steam to Gaijin i do not think is possible, but you could ask Support for a clearer answer. You can find support and instructions on how to contact them here: https://support.gaijin.net/hc/en-us/articles/360000262858-How-to-submit-a-support-request