howto run arduino script?

as you'll see, I'm a complete newbie,
anyway as this seems to be the easiest question here to answer:
how do I start the arduino script? unzipped I found a txt-file, I guess I have to modify it, but how?
and how to continue then?
I am running debian-lenny.
my new duemilanove (328) wants to be played with.
any help welcome and please be fair with me, I read the faqs, did not find what I need and it seems so, that you all are way upon me.
smile, but please answer.