1. Click  "Appearance"
    
2. Then, click  "Background"
    
3. Select  and click your favorite pattern
    
4. Finally, click "Save"

Before	After
( click to enlarge)	( click to enlarge)

Steps:

1. Click on the "Appearance"
    
2. Then, click "background" 
    
3. Then, click the "pure" option 
    
4. Then, click  the color icon   next to the wording of  "background color" 
    
5. Select your favorite solid color
    
6. Finally, click  "Save"  

Before	After
( click to enlarge)	( click to enlarge)