Well, I guess the first step would be to cut out your social life, give up personal hygiene, and become a Mountain Dew addict. That will put you well on your way to be an über geek.
Barring that, you know, you just spend time experimenting. I've been actively using the computer for only 8 years. And only for the last two or so have I really known what the f*** I was doing.
Find yourself some idle time. Dedidcate it to doing nothing but fooling around with different settings. You might want to create a system restore point. (Start Menu -> Programs -> Accessories -> System Tools -> System Restore. Click Create Restore Point, click next, give it a name like "Good Configuration", click create).
Then just mess around. Right-click on your desktop and click properties. Spend some time going through the tabs and menus. This menu lets you control a lot of the GUI of your system. Get familiar with it.
Go to your control panel (Start Menu -> Control Panel). Click around and explore. Check out your System menu and your Add/Remove Software menu particularly. Try not to actually change anything if you don't know what it does, but look around and see what you can do.
There are zillions of tutorials and articles out on the web. Even if you aren't a programmer - many people have computer-focused jobs and don't program - just being very familiar with your computer and what it does can be a good thing. Read articles on your hard drive, and hard drive maintenance. Know about defragging, disk repair, partitioning, boot sectors. Read up on services and start-up programs (you can access these via Start -> Run. Type msconfig). If you are smart and so inclined, you might want to familiarize yourself with the command line a bit (Start -> Run. Type cmd)
Just take your time about it. Read about and experiment with your computer. That is how nearly everyone on these forums came to be so knowledgeable. You don't need to know the nitty-gritty details if you don't want to. Learn at your own pace. Just dedicate some time each day to exploring a new aspect of the computer.