Gradient tricks needed

Hi!

I'm working on a CD cover. I bought a photo from istockphoto which you can see in the second picture. I'm trying to copy/replicate the background, which I will be using throughout the CD back/booklet, so that it has the same feel. See the first image for my attempt. I'm not happy with the result, even though I use the same colors which I copy and paste. I would be very happy if someone could give me tips and tricks to get a better result

My attempt:

What I want to copy/replicate (the background gradient):