And parts are readily available both online and in retail stores around town. Unplug an existing computer and take off the cover. Look at the important parts, such as the power supply, the motherboard, the microprocessor, the memory, the hard drive, the floppy drive, the CD or DVD drive, the video card and the sound card. Just looking inside a PC shouldn't hurt anything. But be careful if you start touching things.
Static electricity can damage a computer's electronic components.
Always unplug the machine first and then touch the case or power supply to discharge static electricity you might be carrying. The safest bet is to buy a static wristband to keep yourself free of static electricity. Replacing a hard drive, adding memory or upgrading a video card is the kind of small step you might consider before trying to build a complete machine from scratch. You'll find that most come with quick and relatively painless installation guides. Don't expect you can build a new computer in a few hours and use it to write that term paper that's due next Tuesday.