Making "tape" is a lot easier than it seems, it mostly just involves pixel and regular painting.

1. Make a new transparent layer. Grab the rectangular select tool and make a nice, thin rectangle. Fill it with black.

2. With a 1x1 pixel brush, use the pencil tool to draw small triangles (5px,3px,1px) on each width side of the rectangle. Fill the entire side with these (use cut and paste after you've made one). View the tutorial image I've attached to see what they should look like zoomed in. Do both sides.

3. Fill the shape with a darker gray (about #dddddd). Grab a fuzzy 15x15 or so (at your own discretion), and make your active foreground color white. Turn on keep trans. in the layers, channels, and paths dialogue box, and, with the paintbrush, paint small 'S' like strokes over the shape. For my example, I did two. Add a dot here or there to throw out some of the uniformity.

4. (You should modify the curves/brighness only after you see how it will look with the image you're going to use it on, but you can do a little fine tuning right now if you please). Use the image>colors>curves tool, and bend the curve more to the upper left portion of the grid: just fool around until the tape looks like you want it to. You could also use Brightness and Contrast. Copy this shape, fill it with black, turn off keep trans. and then filters>blur>guassian blur RLE it 2x2.

5. Merge those two layers, and place it over any image, such as that old photo you might have made with my tutorial. Modify the opacity in order to make it seem clear. Use the transform tool to make it angled (I usually stick to 15º increments). And again, play with the curves if things don't seem realistic enough.

Here's an example of how it is used. Modify the opacity over layers in order to have it translucent.