Background help with sizing?

I had someone make a background for me but its saying that its not big enough so how should I go about changing it so that its the right size?

http://www.simpleimageresizer.com/

  • Upload the image
  • Select Dimensions
  • 640/1280/1920 x 1136 (depending on how many zones)
  • Download image

:slight_smile:

thank you so much!