in this very small tutorial you learn how to change your canvas color.
in adobe photoshop:
1. open adobe photoshop
2. open your image.


3. press "F" key :



4. and if press "F" key again  you can see:



5. in step 3  press  "G" key for paint bucket tool .


    if hold SHIFT + click in your canvas . it change to new color. like this:

   
    you can use any color to change your canvas color. :)