How do I...

Do a search for icons/theme for OS X. I haven't changed any of my icons and as such don't have any firsthand knowledge though I know there's lots of sites out there with icons to download and various apps to help you set up your desktop the way you want it.

Here's one site
And Apple's how to

 

Maybe look into PosterPaint by our very own robbieduncan.

 

For system level icon changes, I use and would recommend Candybar from the IconFactory website.

 

And if PosterPaint is not good enough (yet, it's still getting better every release) then lots of people seem to like Seashore

 

CandyBar is great but sort of extreme if you just want to change one icon. Plus CandyBar isn't free so once the trial is over, it is hard as hell to get rid of some of the system level icons. I suggest simply copying and pasting the desired icon on top of the desired file/drive. This can be done by the following steps:

- Go to an icon website like http://www.iconfactory.com/

- Download a folder of icons (NOT an .icontainer file)

- Highlight (single click) the icon you like, right (ctrl) click the icon, select "Get Info", click and highlight the icon image at the very top, copy it (apple + c).

- Highlight (single click) the icon or drive you want to change, right (ctrl) click the icon, select "Get Info", click and highlight the icon image at the very top, press paste (apple + v).

I recommend changing icons this way if you only want to change the icons for drives or folders. It is also very safe. If you want to revert to the original Aqua/MacOSX icon, just "Get Info" on the icon, select the icon image as before, and now do cut (apple + x).

Enjoy Mac OS X dude.