let me get this straight…..
1 you need a ccontact form
2 you want php to run it
3 you want to store email addresses in a database
4 you want to have the form email a specific person within the sites businesss?
4 have a captcha
5 drop down the target email addresses
if i was doing that i would:
1 make the contact form in html with a hidden field and a captcha entry field (to stop spam)
2 in the php get thte target email to send to
3 make sure the captcha is the same as entered in the html form
4 save the things you want to save to the database
5 send the email out.
about the tutorial you may have to view a few to get exactly what you want, I will look for some later as I am going to work now.