To create a budget, go to GL>>Processing>>Budget. Assuming you are creating the budget for 2021, click the Fiscal Year End down caret and select 12/31/2021.
Then click “Create Budget from Previous Year.” Your budget will populate in the left pane. You can then highlight and edit each budget item as you see fit. Then next year, you can print the “Income Statement with Budget” report in the GL module, to compare actual versus budget values.