Step 1 — Download an appropriate background for your form.

Step 2 — Create an Image Record (bcg.png) and upload your downloaded background.

Step 3 — Create a UI Macro (Back_Form_Incident) and add the image path that was created and you can add some styles for the form as well to look good.

Step 4 — Create a UI Formatter to call UI Macro and you can add this formatter to the table (Ex- I have taken for incident) using form layout.

Step 5 — Add Formatter to the form (incident).

Step 6 — You can enjoy the changes for your relevant form (incident).