Locating Celestial Pole in your images, and faking star trails
Published sometime in 2016, when I was 16
Since this tutorial involves a lot of diagrams and some math formulas, so I would simply give you a pdf file of the tutorial.
Note that you do NOT necessarily need to locate Celestial Pole in your images to fake star trails. You only need to do so only if you want to fool seasoned astronomers (and honestly I don't think they'd fall for it). That said, if you think you've got the brains and can tolerate a bit of math, then I think it's a pretty good astronomy exercise