Transparent Tape
1)
Create a new image (mine is 100×100 pixels) and change the background canvas color to a medium color (I chose #009999). To change the canvas color go to Modify | Canvas | Canvas Color…
Click on the Rectangle Tool (U) 
and draw a rectangle in the middle of your canvas. My rectangle is 80×20 pixels.
Take a look at your property inspector and change the Stroke Color to white (#FFFFFF).
Now change the Fill Style from Solid to Gradient. Next, click on the Fill Color swatch next to the Fill Style Menu to change the gradient’s colors. Change the start AND end color to white (#FFFFFF) and change the opacity of each color to 50%. See example at left.
Your image should look like the image below.
2)
Select the Pointer Tool (V or 0) 
and click on the rectangle that you drew in Step 01. Press CTRL + SHIFT + G or go to Modify | Ungroup. This step converts the rectangle to a path and allows us to modify/add vector points.
Next, select the Pen Tool 
and zoom in on the rectangle (I chose 200%). Move your mouse over to the left end of the rectangle (your cursor should change to a pen with a +) and click to add 5 different points down the side of the path. See the example below. Do the same thing to the right end of the rectangle.
3)
Now, select the Subselection Tool 
and click on the rectangle with all of the points that you just made. Click and drag every other point inward a few pixels. You are trying to make the ends of the rectangle look like torn edges. See my example below.
4)
This is a tough step. We want to give the tape some depth with a dropshadow but we can’t just add a live effect because it will show under our transparent fill.
To remedy this, duplicate your tape layer (CTRL + C and then CTRL + V) and select the bottom tape layer. In the Property Inspector, change the Fill Style from Gradient to Solid.
Now go to the Effects Area of the Property Inspector and click on the + Icon to add an effect. Choose Shadow and Glow | Drop Shadow and change the options to match the option below. Be sure to click on the Knock Out checkbox or the effect will not work.
When you are done, your image should look like the example below.
Final
Now all you have to do is Group the tape layer and the shadow layer (CTRL + G) and rotate it. Paste it over the corners of a picture to make it look like tape is holding it up.
In my example below I added some scratches with the Brush Tool and a hair to make it look even more authentic.
