Create a new document 400x300 with a white background, create a new layer called "folder". Select the "polygonal lasso tool" and make a selection like this.
Fill the selection in black then add these layer styles.
You should be left with this.
Create a new layer and name it "shine", select the "rectangular marquee tool" and draw a selection like this.
Fill it with a white gradient.
Now with the "shine" layer still selected hold "ctrl" and click your folder layer. Now goto "select > inverse" and hit the delete key, you should be left with this.
Lower opacity to about 50-60%.
Select the "rectangular marquee tool" again and draw out a small rectangle under your folder layer.
Fill with the color black, then "right-click" your "folder layer" and goto "copy layer style". Then right click your new rectangle layer and goto "paste layer style" you should be left with this.
Press "ctrl + T" to free transform your rectangle, select the bottom middle anchor point and drag towards the right whilst holding "ctrl" on the keyboard. You should be left with this.
That's it all done.