It's as good as impossible to participate in modern society without regularly interacting with a computer, in one form another. Despite this, startlingly few people actually know how they work. This site aims to improve this by having you build a computer from scratch. Good luck!
Okay, we're not throwing you in the deep end quite that fast. The building process is divided into small puzzles; all you have to do is produce a circuit that complies with the given specifications, and you'll have built a working computer before you know it.
You can browse through the levels in whatever order you want to, but do note that you'll only have access to components you've already built. If you want to produce a computer with just raw predicate logic, we won't stop you, but if you work through all levels marked as important roughly in order, your life will be a lot easier.
Now, try the first level to get your hands on the basic gates, and to get a slightly more in-depth explanation of what you need to do.