transistor - 7:05 pm on Oct 23, 2002 (gmt 0)

The "root folder" almost always means the main directory of your site (that goes for every site you might host).
Let's say, you have a domain foo, and the "root folder" on your server is:
/dir1/dir2/dir3/foo/, now that's where robots.txt belongs to.
It sits right next to your main index.html (or whatever suffix you've got).
That's it.

Oh, and beware of text editors, make your robots.txt file with Notepad or BBEdit (or maybe even use Pico to create the file on your server if it is some kind of Unix).

If you have uploaded your robots.txt file and still in doubt, use the Robots.txt Validator at SearchEngineWorld [http].