You can click on the the "Suggest" link and it will suggest a budget based on the last three months of transaction history, or you can click on "Setup" to set up your budget manually:

Set up Budget

You can also click on the "Edit" button next to each category and input your "allowance" and any keyword rules you wish to add for the given category:

Set up Budget2

Set up Budget3

Click "Save" when finished.