I'm a fan of MS Excel _ my apologies for those who have issues with Microsoft _ because I find its powerful calculations are easy to manipulate to help me better understand my finances. It doesn't really matter though which spreadsheeting package you use so long as you are able to calculate your amounts effectively. There are commercial budgeting worksheets available but if you want to create your own its a simple process.
Next, you will want to fill out a monthly financial report worksheet where you record you income and come up with your net spendable income after taxes and any charitable giving. Then you want to take your totals from your monthly expense record worksheet and fill in all amounts in the categories such as household, food, medical, transportation, and recreation just to name a few. When you total up your expenses and subtract them from you net spendable income you will see if you have a surplus or not.