make a new file, and make a shape on a new layer. i made this one with the path tool. select the shape [(strg)+(left mouse click) on the layer.]

select the linear gradient tool. make sure that the background is white and the foreground is black. use the gradient tool from the top left to the bottom right corner of the selection.

keep the selection and contract it by a few pixels (select -> modify -> contract). now feather the selection [(select -> feather) or (strg)+(shift)+(d)]. now use the linear gradient tool once again, but differ with the direction and angle. try how variations work out.

the background is also made with two simple linear gradients, where the top gradient has a layer mask, where clouds were added. i also made a simple drop shadow (just take the selection of the shape, feather it, fill it on a new layer which should be between the shape layer and the background layer, and move it a few pixels to the right/bottom.