It's pretty easy to do. Start by taking two pictures one right after the other, but take a step to the right after the first. Then put them side by side on the screen, swapping them so the one you took after stepping to the right is on the left side. There's a program called Stereo Photo Maker that will help line them up for you like that, as well as adding a border and text, among other things. I don't remember where I got the program, but Google the name and you should find it easily enough. That's how I found it.
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