This is a page under Accounting - Budgets.

You can create a New Budget from the three dot menu near the top right. You can name it, and then choose what it is linked to by clicking Add Link. You can either have it be linked to a Company, Property, or Unit.
If you do not Add a Link, it will show data for all companies in the system.

Once you create the Budget, you will see all the values you can enter from this screen.
On the left you will see the Actual data from the system. By default it shows the last 3 months, but you can change that from that dropdown to show more or less months.
You can also use the arrows to scroll to see more historical data.

On the right is the Budget. Here is where you will enter the data that you plan to have for your budget.
All of these will just be manually entered fields.
We also have a few tools to update more than one field at once.
The first is the ability to change the dropdown from Month to Year, and then you can add a value for an account for a year, and then if you switch it back to month, it will divide that evenly between all the months for that year.

There is also a 3 dot menu next to every value in the Budget, as well as next to the entire month at the top. From here you can click on Apply Formula.
Here there are some options to apply amounts to every month, or adjust each month by a certain amount or percentage. This way you can update multiple months at a time for a given account or all of the accounts. 

There is also a three dot menu for each month under the Actual section, so that you can copy all of those values to use for next years budget.

The graphs that display will reflect the values in that particular section. It will show the value for that account and show how it changes over the course of the next months or years. 

There is also a blue line that will show under the month or year headers in the Budget section, if there is data in that section. So if there is no blue underline, you can tell that there are no values entered for that section for any account.

Once you are done entering data in your budget tool, you can save it by clicking the three dot menu near the top right.
There will be a warning message if you try to leave the page before you saved your budget updates. 

You can add additional budgets from the three dot menu near the top right.

Then we also have a report to show all of these values in more detail and compare the actual values to the budget. This report is called Budgeting Report, under the Accounting section of the Reports page.