AThe stack requires support of PHP, thus it will automatically add a .php extension to the page. Due to the php requirement, it will not function correctly in Preview, you will see a warning in the page and the Print Areas & Print CSS will not be applied correctly. Simply Publish to see the proper functionality. If the page had an .html extension before adding PrintMe, then a new page with a .php extension will be created on your web server. You will need to look on your web server with an FTP program, such as Cyberduck, find the old .html version of the page and remove it. This is necessary, as web servers will often continue to show the old .html version.
In order to find out the divs to Print Areas, you can use the Print Helper at the bottom of the controls & then preview the page using File > Preview Page in . When you click on areas you want to print, it will show a popup window with divs that wrap that area & the area will flash yellow afterward. Note: Be sure to turn off Print Helper before Publishing. Or you can manually find out the name of the Print Area divs by right-clicking on elements and select inspect element. If you don't see inspect element when right-clicking, you will need to go to RW's Preferences > General & check Enable Web Developer tools. Once you know what divs wrap the parts you want to print, then just enter them in Print Areas, EX. #one, #two, etc.
Note: if visitors don't click the Print button or Print nav link and instead manually print from the browser, then the custom print functionality won't work. This is expected, as most viewers will actively look for a visual print link when printing.