Welcome to SR!
You start by not picking up that drink. If you're having trouble not picking up, tell yourself you won't pick up right now. Just for these next couple of minutes. Give the urge a chance to pass. Make it through today with those moments of not drinking right now. Don't worry about tomorrow until tomorrow comes.
I saw your post in the other forum. There is good news. You never have to do this again. This can be the last time.
Best wishes to you.