Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Drag the application to the trash. Empty trash...

Also, if you're picky, run a search for any files with the apps name to weed out preferences and the like.
 
There are apps that will go around and look for those pesky pref files. I use "Clean-App", it's shareware, but I know there are some freeware ones out there that might do the trick.
 
Like a demo or something like that...how would I unsinstall it?

It's good to see that you're diving right in, and getting really involved with your Mac.

To save you some time waiting on responses, try looking here (http://guides.macrumors.com/Mac_Beginner's_Guide) first. It may just answer your question.

Also, I'd recommend checking Amazon.com, or your nearest MegaBookStore like Barnes & Noble or Borders, and grabbing a good Mac OS X guide, like one of the many listed here (http://www.amazon.com/s/ref=nb_ss_b...&field-keywords=mac+os+x&Go.x=0&Go.y=0&Go=Go), for example.
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.