well, you'll need a mail script. Are you using .php? If so, I can help. I use the MailIt script for all my sites.
Take a look at
www.dilu-art.com/contact.htm
The client fills out the form, sends it, then 3 things happen.
1) You get an email with the info they submitted.
2) They get sent to a welcome page.
3) They get sent a personilized email from you (your server) thanking them and letting them know you will contact them soon.
If you aren't running php though, then I don't know. There are various mail form scripts all over the net though available for free.
Let me know if you want this script, I'll .zip it and attach it.