There are lots of uses, but none of them will be a 'correct' answer.
Off the top of my head:
- Over time you will see what expenses are increasing/decreasing.
- You will see what expenses you didn't realize were so high. (I had a friend who had two candy bars every day, not realizing he was spending $90 a month on candy! He switch to buying them in a box instead, and saved $50 a month. Then he went on a diet but that's a different story.)
- You will see how much your expenses are in relation to eachother. "Hmm, I get 30 hours a month out of this online game that's $15, but I get 3 hours for $20 at the movies."
- You will see how much your expenses are in relation to your income.
But none of these are a "correct" way. The only correct way is for you to establish what your financial goals are, and then find tools that support you in analyzing your situation to attain those goals. And the goals are so much more important than the tools. The tools are great. You're already a step ahead of most people with... planning your monthly budget. I know it sounds strange, like it'd be a simple basic necessity, but most people don't do it! They just make sure before they spend something they have money for it (hopefully.)
Rather than ask what the correct way to use your spreadsheet/budget is, I would ask what information do you want to know about your finances?