DB, in order to get render frames working you have to have a renderer installed on your system.
Go to Scribus "Preferences -> External Tools" to see the list of possibilities - LaTeX, Gnuplot etc.
Installing any of these tools will depend on your OS and which one you want to use.
If you want to use LaTeX (which the wiki example uses) on OSX I can recommend BasicTeX (see
http://forums.scribus.net/index.php/topic,668.0.html). It's a cut-down version of the full LaTeX and seems to work well with Scribus.
However, you may already have LaTeX installed but your "paths" aren't set-up correctly.
On OSX you can use something like muCommander -
http://www.mucommander.com/ - to find where the
pdflatex executable/link is. (Finder won't do it, unless you've set various hidden options.) Then you can add this path to the Scribus
pdflatex command (in the External Tools section).
On other OSes maybe someone else reading this can help. (Unfortunately the wiki isn't particularly extensive when it comes to explaining this but there must be so many OS/Renderer combinations that it'll be near to impossible to get a comprehensive list, not to mention keeping it up-to-date with every addition/change.) If you give your system details it will help someone to help you.
Anyway, good luck.