If you are looking to customise your Dashboards more with tracking specific ‘Tracking Categories’ or ‘Classes’, then this article will detail just how to do that!
Make sure you are on the ‘Dashboards’ tab:

From here, click ‘Add a Chart' and either type into the AI chat box a specific chart you are looking to create, select one from the existing charts or click “Create new chart” to create a new chart from scratch.

I have chosen an existing chart for ‘Revenue’ in this example:

Make your way to the 3 dots icon top right of the chart and click ‘Configure Chart'.

On the left under ‘Chart Series’, click the series you want to edit or add a new one at the bottom of the screen by clicking ‘Add Series’.

For this example, I will just edit the existing series.
Next, you want to click ‘Metric’ and the ‘Formula’ option to enable you to select an acount code and tracking category combination. (Note - if you have already set up the desired combination as a defined ScaleXP metric in the Metric Library, then you can instead choose that Metric here).

From the ‘Formula’ screen, search for the account or account group you wish to use.
In this example, I'm using ‘Total Revenue’ Financial Group from Xero
Click ‘Done’ once you have selected it.

Click on your newly added account or account group and click the cog icon.
This will bring up the option for you to select your relevant ‘Tracking Categories' or ‘Classes’ that would like in the chart for that data series.

Once you are happy, click ‘Done’ and then ‘Save’ to load in the ‘Tracking Categories’ or ‘Classes’ you have selected.

Ensure you save the overall chart by pressing ‘Save changes’ top right to see this live on your Dashboard.

For more information about chart editing see Getting started with Dashboards.
For more information about reporting by Tracking Code or Class, see these articles:
How to create a new report from a template
How to add Tracking Categories or Classes as rows in your Reports
How to report on tracking codes for Customer data