syntax / method for executing an emacs lisp function?

[farbot]

I'm writing a language mode for emacs, but have never used emacs before
(the mode is for others to use).  I've searched for hours, but can't
find the incantation I need.  I'd appreciate some pointers to specific
help files or techniques.

I'd like to run the regexp-opt command to optimize my list of keywords.
 For example:
(regexp-opt '("TRUE" "FALSE") t)

I've tried a bunch of methods from inside emacs, but it always says
there is "no match" for regexp-opt.  I've had the best luck on the
command line using 'emacs --eval' option, but one of two things
happens: 1) it dislikes my syntax (badly placed ()s, unmatched '), or
2) it accepts the syntax, and opens emacs and shows a *scratch* buffer
in "(Lisp Interaction)" mode -- but there are no function results
present.  In the *Messages* buffer, I find my command echoed, but still
no function results.

I also tried typing commands in Lisp Interaction mode -- but neither
return nor enter makes them execute.

I'm thinking I need to figure out how to execute from a file instead of
the command line -- since some of my keyword lists are quite long (not
sure how much fits on the command line).

I'm running emacs 21.2.1 from the command line on Mac OS X 10.4.6.
Thanks for any pointers you might have.