In version 1.3, I add features required to manage categories and a simple budget. All this can be done from a single page, as shown in the screenshot below (with randomly generated data).
At top/left section is where you manage categories. All financial transactions must be itemized (or categorized). In the context of categories, you then can create a budget (as seen at top/right section). A category can have any number of budget items, each specifying budget amounts for each month of the year. Annual and monthly totals are displayed at bottom for convenience and quick reference.
My philosophy on personal budgeting is that a budget should initially be designed around expenses only (as opposed to incorporating income). I take this approach for two reasons: (1) everyone has expenses regardless of income, and (2) knowing expenses first helps shape an informed strategy for obtaining income to cover the expenses. A budget is simply rules on how you plan to use money (and doesn't necessarily mean you have that money). Income should later be considered when balancing the budget (in light of actual financial activity) and for forecasting. Once you know how much you must spend, the question then becomes: "how shall I get all this money?". An expense-only budget also helps bring to the forefront your lifestyle and priorities.