Help!!!

Ok guys I need your help. For the last week and half I have been working on a new background for my blog. I have it up right now. But on my home computer it is centered with two big white strips in the left and right making my text hard to read because its not on the text background. Does that make sense?


Then on my work computer it comes up fine and then disappears and goes completely white. But The Hubs work computer has it perfect just they way it should be.

Can you tell me how you are seeing it? I am so frustrated and am lost. I don't know how to fix this. Obviously it is coming up different on different computers. I need to figure out how to get this right.

Thank you!