A passbook shows three things on every line: what came in, what went out and what is left. A budget can work the same way.
Write your income for the month at the top. Underneath, list what goes out on fixed dates: rent or mortgage, utilities, insurance, loans. Then the things that change: food, fuel, presents.
Whatever is left is what you can save or spend. If the number is negative, talk to us at the branch: there is often more we can do together than on your own. General information, not advice.