There are a few different ways that you can create a fixed budget. One way is to track your spending for a month or two and then use that information to create a budget that you can stick to. Another way is to create a budget based on your income and then make sure that you don't spend more than that each month. Whichever method you choose, the important thing is to be realistic and mindful of your spending.
Creating a budget can seem like a daunting task, but it doesn't have to be. Start by evaluating your spending and income, and then make adjustments as needed. If you're not sure where to start, there are plenty of resources online that can help you create a budget that works for you.