You have to Insert a Form and the form fields from the Insert Menu.
Choose from text box, textarea, radio button, checkbox, submit button, file
field, (for uploading files from a form),dropdown box .
This is fairly straight forward once you get the hang of it - to adjust
properties of each field, double click the field to adjust the
properties/options/styles etc.
Then you have to go and right click on the form you created and click Form
Properties and follow through the options presented to set up the form handler as
frontpage extensions which give you a choice of sending you an email, send it to
a database or text file (or combinations of the three e.g. send email and write
to text file on server).
You can also use a third party cgi/perl program, but since you seem to be a
beginner here, but this is an advanced topic and unless you what you're doing
CGI can get a little messy.
For further help, look up Frontpage Help and search for "Forms". or Google.com
for "Frontpage Forms" or "Frontpage Tutorial".