Normally if the background was one solid colour I would take a sample of that and fill the whole area in with that colour then put your new text on top.
Looks like it is a gradient.
So take a sample of the top with the colour picker as the foreground. Then a sample of the bottom with the colour picker tool again as the background colour. Select the area with rectangle select and with the gradient tool select the foreground to background gradient in linear shape. Put your cursor at the top of the picture in the centre (use guides to be exact, vertical at 50% should be enough) and draw to the bottom. Select > none. Then with the text tool, select area over picture and put new text in. Centre align it if need be.
Looks like it is a gradient.
So take a sample of the top with the colour picker as the foreground. Then a sample of the bottom with the colour picker tool again as the background colour. Select the area with rectangle select and with the gradient tool select the foreground to background gradient in linear shape. Put your cursor at the top of the picture in the centre (use guides to be exact, vertical at 50% should be enough) and draw to the bottom. Select > none. Then with the text tool, select area over picture and put new text in. Centre align it if need be.
