Originally Posted by Starson17
Drag book into calibre's GUI, right click on it, choose convert.
You have probably already solved the problem but for all the other people who will consult google after you, here's what you do.
Fist drag the epub into the list of the Calibre standard interface.
Then right click on the book you want to convert and select convert individually
In the following screen with all the output options, on the top right hand corner of the window there's a small pull-down list of output options which you need to set to PDF (you'd think they'd make such a fundamental option a bit easier to spot wouldn't you?)
Hope that helps