2011 Theme Replace Title & tagline with logo

which theme you are using ? exactly name it

go to settings or may be you have wp themes so you get the background option in themes -> appearance -> options

I tried the background option in themes but nothing happens when I upload the file.

if you are using themes like wp themes so contact the support google it type the theme name support then contact the support.

Yes, I am using the twenty eleven WP theme. Thank you. I appreciate your help.

you welcome… again installed the theme you will got the option.. or you can manually do it with style.css file