When working with a word document, you may need to highlight one or more paragraphs to make them stand out. Please follow the steps below to add the color background to a paragraph.
Step 1: Select the paragraph(s);
Step 2: Click the "Home" tab from the ribbon;
Step 3: Click "Shading" in the "Paragraph" area, and select a color (e.g., light orange);
Step 4: You will see the paragraph background is now light orange.
Alternatively, you can add a rectangle shape to cover the paragraph, then to change the shape color, which is same procedure changing page color only on one page in the word file.
If you want to use an image as the background, please refer to how to add a picture background to a paragraph in Word.