In case you need to add a picture background to a paragraph in the word file you are working on, please follow the steps below:
Step 1: Click the "Insert" tab from the ribbon;
Step 2: Click "Shapes" and select "Rectangle" from the drop-down shapes;
Step 3: Draw a "Rectangle" shape to cover the whole paragraph;
Step 4: Click on the shape and click "Shape Fill" in the "Format" tab from the ribbon, then select "Picture" from the drop-down list;
Step 5: Navigate to the picture location or use Online images;
Step 6: If the shape comes with a border, you may need to click the rectangle then select "Shape Outline" and click "No Outline" from the drop-down list;
Step 7: Click "Wrap Text" and select "Behind Text" in the "Format" tab.
If you only need to add a color background, please refer to how to add a color background to a paragraph in Word.