I just got Calibre the other day and immediately ran into a problem because I couldn't DL my books to my Kindle Fire HD from my (Windows XP) pc. I was sent a link to Kovid's note on a patch to address this problem.
Now is where I expose my newness.
Kovid says to open the preferences and insert a bit of code for a patch. Only I am looking all over my copy of Calibre and I don't see a button or a menu that includes Preferences. I looked at Kovid's Utube video where he tells how to use Calibre. It shows him accessing the programs Preferences by clicking a button at the top of the screen. I'm looking at my copy of calibre on my computer and the menu at the top of the screen is a row of buttons that starts with "Add Books". It looks like there is another line of buttons in the Utube video. If it's hidden I just can't find it.