To change the background color in Adobe Illustrator, first, ensure your document is set up. Select "Window" from the top menu, then open the "Artboards" panel. Click on "Edit Artboards," then select the desired artboard. Choose the "Rectangle Tool" to create a rectangle that covers the entire artboard. Fill it with your desired color by selecting "Fill" from the toolbar or using the Swatches panel. Finally, send the rectangle to the back by right-clicking and selecting "Arrange" > "Send to Back."
