Background 'LIGHT' Technique

I have a question on the league news template - the background appears to have a 'light' shining on the background - what it this technique called? I have GIMP and wish to achieve something similar on background for the virtuemart part of the league news template (i am building myself)

As I remember it was a subtle radial gradient (with relatively high opacity value) over the template background image. Sometimes for effects like this we're using the layer blending options in Photoshop like "overlay", but I don't know how to achieve it in the GIMP.