How do I reduce spam from formmailer?

[Yani]

Ok, I'm a xhtml coder and not a programmer yet. I have set up a form mailer on my website and have been getting a lot of spam.
I have researched it and tried the form mailer in comment tags. Didn't work. I also found the option to insert a hidden field that should not be filled out when a real person fills out the form. I found some scripts for cgi to reject those emails. I don't know if those would work with asp and I don't know where to put them.

Does anybody have an html or javascript code that I could copy and paste? Same thing with catcha? And instructions with it where to put them?

Sorry, I'm a real beginner...

[scrupul0us]

things that will help

1) validate fields and their types before mailing
2) limit optional fields
3) validate that the domain of the senders email address exists
4) captcha
5) limit the submissions from an IP to one a day
6) limit the submissions from a specific user agent to one a day
7) disable submissions for bots
8) in lieu of captcha, add a simple question (what is 2 + 2) to the form that bots cant fill