i was wondering - if i choose a font on my website that is not on the
viewers computer, which font will he see?
Depends on what you mean by "choose". They'll probably get some local
default, according to their own computer's settings.
You could also try reading the thread "Typeface selection in CSS" from a
couple of days ago. In practical terms, you can reliably choose between
serif, sans-serif and monospace fonts, but not much more detail than
that.
and is there a way i can get my font onto there computer?
Yes, but it's lumpy and barely usable. It's very M$oft-specific, IE only
(AFAIK), is fussy about which fonts it works with and is generally a
pain to use. Try searching for "WEFT" (on the M$oft site). It's rare
that you can find a freeware font that it's technically capable of
working with, let alone licensable for. Proper commercial fonts are
often more reliable, but are less likely to permit this sort of use by
their licenses.