This tutorial will teach you how to get those trendy little x's on your icon. Of course, you can just use a brush, but I am usually more happy with the results doing it this way, as this method actually fits the image. I will try to remember to make a brush of the halftone layer and post it at the end of the tutorial, just in case you'd rather do it that way.

First, prepare the base you are planning to use. I found a pic of a cute cowboy (Owen Wilson) to use for the example image.

Now we need to make a duplicate of this image. To do that, right click on the info bar at the top of your image, and choose "duplicate" then say OK in the pop up box. Now you are looking at two images exactly the same.

Make sure the new, duplicate image is selected, and go to Image>Mode>Grayscale. (Note: there is a much better way to convert an image to black and white. I would never do that with the method I just said, but the other way is a whole different tutorial on it's own, so I'm choosing the easy way for now.) You will get a pop up box asking if you want to discard the color information. Click Yes. Now you have a black and white cowboy cutie.

Now, with the same image, go to Image>Mode>bitmap>Yes on the flatten layers, then you will get another pop up box. Set it thusly:

If your input is NOT 72, then don't put 72 in your output box. Make the output match the input, whatever it is. When you click ok, you will get another pop up box. Set it thusly:

I think the frequency can be anything between 500 and 1000, doesn't seem to make much difference to me, but you might want to play around with it a bit.

Now our base copy looks like this:

Mr. Wilson is not quite as good looking as he was. Ok, let's fix him up.