How do I move the harddrive icon onto my Dock?

I'm not exactly sure what you mean by the "taskbar" of your Mac OS X system, but there are two possibilities: either you're talking about the Dock, which pops up on the bottom of your screen and offers shortcuts for launching applications, or you're talking about the left side of your Finder windows where you have various icons already. I'll answer both questions.

First off, to get your hard disk to show up as an icon on the Dock, you simply need to drag its icon from the Desktop onto the Dock itself. Of course, you might not have a disk icon, so in fact the first step is really to go into the Finder and choose Finder --> Preferences..., then select the "general" option:

You need to ensure that you've checked your hard disk choice so that the icon appears on your desktop. Now you can drag and drop that icon onto the Dock:

Once you've done that, the icon's on the Dock and if you click and hold down the mouse on the disk icon itself, you'll find that it pops up a nice hierarchical menu:

Cool, eh? :-)

To add your hard disk to the Sidebar in a Finder window's even easyer: click on Finder --> Preferences... then click on "sidebar" and choose Disks:

That'll get you a hard disk icon on either or both places!