I'm broke

It's become quite obvious to me that I simply have no idea how to properly manage my money. It's been over a month now where I am literally living paycheck to paycheck. Granted, I did have to pay $500 to get my car fixed a few weeks ago and that put a dent in my bank account. But why is it that I can't seem to just keep the money that I'm making instead of letting it run through my fingers like water? I need to take a class or something, but only if it's free.