Hi @andycski …welcome to the Community.
Your Categories sheet is your monthly budget for each of your categories. By default, it only has zeroes in it because it is ready for you to enter your spending and income plan for each one, in each month. Does that make sense?
Assuming that you expect the same numbers in each month in a given category, the Categories sheet, by default, will copy your January’s number across to the other months in the year. You can override any of these numbers at any time by simply entering a different number. Some months can remain zero, too, depending on your expectations.
Tiller then compares your actual activity in each category against your budget and produces several, cool summary items to help you see how you’re doing compared to your plan.
Here is a link to a post with a great budget-prep tool. Take a look:
Does that help?
Best.