There's no code to include, you just go to the form properties (right-click
inside the form) then set the options to send to your email, or to text
file. there are other options - to send to a database (ms access commonly)
and to use a thirdparty server side form processor script, written in asp,
aspx, php, perl etc.
Use the first option where your server has the FP server extensions
installed, and configured for sending email.
otherwise, yes, you may need a third-party mail-sender script.
Your host themselves may even offer an alternative to Frontpage ext (if they
don't support Frontpage extensions, or even if they do). They might use a
script they "trust" to run on their servers.
My host
www.spiritconnect.com.au for example, uses "CPanel" for its control
panel for web hosting accounts (Linux accounts); Cpanel has options to
install various scripts on my web hosting account including form mailers,
bulletin boards, forums and even shopping carts, plus admin & config tools
for the mysql databases.
Anyway, check with your host - they may have configured whatever control
panel program (like CPanel) they use so you can install a similar script for
sending email from a web form.