How to Create Budgets In macOS
To create a new budget in macOS, click "Add New Budget…" button in the left sidebar. You might need to expand Budgets section to make this button visible. After that you will need to provide budget attributes (details) described here.
How to Create Budgets In iOS
To create a new budget in iOS, select "Budgets" in the main menu of the app and then tap on "+" button in the upper right corner. After that you will need to provide budget attributes (details) described here.
What Happens Next
Once a budget is created, you will be able to see its details in Budgets section of the app. The details will include remaining balance, amount spent in the current period and when the next period is due.
Should you decide to update your budget amount after some time, you will have an option to apply the new balance only from the current budget period. This way you will always be able to keep your budget history complete.