A couple of things spring to mind, but first I have a question for you:
If you made the site in Dreamweaver, why do you want to upload it from FrontPage ?
Dreamweaver is more than capable of publishing the site and unless you want to add some FrontPage extension driven stuff, I can't see the point. You're making things more difficult than they need to be, unless you no longer have DReamweaver on your system of course...
Now, the first thing you should do is import all files into FrontPage, open the index.htm file - if it's index.html FrontPage may rename it to index.htm during the import, so you will need to fix goosed links on your other pages. Save the open index page and see if the publish option has becmoe active.
If not, open your web site from the web, not on your local copy.
Click on File, Open Web (this depends on your version of FrontPage) fill in your FTP details and once the FrontPage knows where your site is on the web it will allow you to publish.
There are a couple of other things to check but this should get you up and running.
Finally, unless you want to take advantage of FrontPage Server Extensions or the really nice synchronise options in FrontPage 2003, you might just be better off with a dedicated FTP client.