what is the correct procedure to make us as a legally 50 / 50

Put your 50/50 deal in writing. Have the LLC be a Member manager. If you've already set it up as a Manager-managed LLC, make the both of you co-managers. Get your name + "partner's" name on the bank account signature card.

You should also reserve certain powers to yourself and to the other person. The problem here in a 50/50 deal is that this could result in a deadlock. Then you're headed to court to resolve it.

There's lots more. You need to speak to an attorney to write this up correctly or you'll be stuck with what the LLC statute says.

Disclaimer. I am not your lawyer. The information provided is merely for educational use. Contact a lawyer in your state.