Establishing equity in a startup

I have a startup firm that is incorporated as an LLC and ready to go, however there is the issue of equity. My business partner and I would like to split 35 & 45 respectively, with 20 left for future allocation. A friend mentioned that the way to establish this, officially, is to record it in a type of corporate minutes. Does anybody know what process he is referring to and what the way to do this would be?

Thanks!