I don't really know anything about computers. At all. I can take out and replace a hard drive, which is what I did recently with my computer, but that is it. Could you link me to pages helping explain how the parts of a computer work and what the differences between specific specs on items are? I would like to upgrade my computer and I would like to know what I'm doing before I buy anything.
I'd recommend watching TekSnydicate's channel on YouTube, specifically the how-to videos. LinusTechTips is another great channel that also has many instructional videos. Newegg.com's YouTube channel also has a lot of build guides. I don't know any websites that break things down Barney-style, but if you have a specific question, chances are it can be found on Wikipedia or on this forum. I find the easiest way to search for something specific on the forum is to type "site:teksyndicate.com (query)" into Google. You can do this with any website. Good luck and welcome to the community!
Many youtube videos, like the ones stated above, will help newbies a lot. If you have a problem, Google is your best friend. Old forum threads are also helpful.
Your Local library should also have books and magazines that will be able to help you. Also check out your local community college, in my area they offer a computer building course during the summer break.