To have meaningful input into the decisions about how to raise and spend city money, citizens should understand some budgeting basics...
The city cannot spend money without an approved budget -- Each year, Philadelphia's Mayor and City Council must agree on a plan (and establish the legal authority) to generate funding and spend the public's money on city services from firefighting to trash collections. Unless a city budget is established legally, the city cannot spend money.
The budget covers spending from each July to the next July -- Each city budget extends for a single year beginning on July 1st and extending to the next June 30th -- the city's fiscal year. Before each fiscal year starts, the Mayor proposes a budget to City Council, City Council debates the details of how the money is to be raised and spent, City Council adopts the budget, and it is signed into law by the Mayor. It takes a majority of City Council (nine of 17 members) to pass a law (including the budget). If the Mayor disapproves of a law and vetoes the law, a super-majority of City Council (12 of 17 members) can vote to override the Mayor's veto and enact the law over the Mayor's objection.
The city raises and spends nearly $4 billion each year to fund city services -- In fiscal year 2008 (which began on July 1, 2007 and ends June 30, 2008), the city will spend more $3.9 billion from the General Fund, which is the portion of the city budget that pays for the services we generally think of as "city services" including police protection, trash collection, park maintenance, etc.
There is actually much more to the budget than what we usually think of as the budget -- The entire city budget covers about $7 billion in spending and includes other funds (including money raised and spent to operate the airport and the city's water utility), but when we speak about "the budget" we are generally talking about the General Fund. Similarly, we sometimes talk about the Operating Budget because when we refer to "the budget" we are generally talking about the money we raise and spend to operate government agencies each year, for example, the salaries of police officers. A separate Capital Budget is also approved and adopted each year to fund long-term obligations established as something like a mortgage for a home, for example, the construction of a police station. The "payments" on those long-term obligations become part of the operating budget just as a mortgage payment becomes part of an annual household budget. Spending on city schools is not part of the city budget. The school budget (which accounts for another $2.5 billion in spending) is prepared by the School Reform Commission and is independent from the city budget.
Resources for further study:
The Pennsylvania Intergovernmental Cooperation Authority presents detailed information about revenues, expenditures, and trends in its Citizens Guide To The Budget. The City of Philadelphia annually publishes a Budget In Brief and a Five-Year Plan (links are to the Budget/Plan submitted by the Mayor to City Council in January 2006).
That's basic budgeting...for more information about what you need to know to affect decisions about how the city raises and spends money, follow the links below for intermediate information and advanced advice.