Download the template you want to use then unzip it. Double click on the file you downloaded most windows computers have a program to unzip the file. If not you can download one at http://www.winzip.com (mac users use maczip http://www.haase-online.de/dirk/maczip/).
When unzipped you will have a folder with all the pages and images for the template.
Now to get this into FrontPage. Start FrontPage and go to file > new > web and create a new FrontPage web. Now save the web and remember where you saved it and the name of the web. Now open windows explorer and move all the files from the templates directory into the FrontPage web folder you just saved.
Close and open FrontPage then open the web you saved before and you should see all the template files in FrontPage. Then you can work with the pages just like they were created in FrontPage.