French cleats are a simple way to hang things on walls while allowing easy repositioning. One bevelled cleat is fastened to the wall and the other is fastened to whatever you want to hang. One catches the other and gravity does the rest. French cleats are commonly cut at 45 degrees but I prefer to cut mine at around 30 degrees. This makes them easier to lift off the wall (especially way up high) without sacrificing security.
You can also use Google image search to research a project. Unlike the PDF search, the image search provides a photo of what the project will look like, which is helpful in determining if you want to pursue building it. By doing an image search for how to build a step stool, you will have a ton of options that all lead to woodworking plans of various quality. (The how to part of these is important—otherwise you’ll just get pictures of step stools.)