As recommended by Bobby Phoenix, I had copied the fonts folder from Windows to Ubuntu and put it on my desktop. I installed Fonty Python from the USC and I then made a Pog of the fonts I want to include in Mozilla Thunderbird (to start). How (by what process/es) are the new fonts (within the newly created Pog) placed within the particular program that I want (in this case Thunderbird)? P.S. what does Pog stand for? P.P.S.Thanks for your help Bobby
Fonts are installed in your font folders. All installed fonts should be available in the programs. To install a font just double-click on the font-file (on your desktop, as you said) and install. There are also lots of fonts available from the Fonts-Section in the Softwarecenter! There is a package called ttf-mscorefonts-installer, which installs all default Windows-fonts on your system (Arial, Comic sans, Helvetica etc.).
It is not neccesary to use programs like Fonty Python, but it helps to manage huge font collections. What does Fonty Python? It just stores groups of fonts (pogs), to install and uninstall them easily. This can be usefull, if you want to use a set of rare fonts in a design project, which you will never again use. Finishing your project, you can uninstall all those fonts in a pog with one click.
Where are your fonts? You can see a list of your fonts in the file /etc/fonts/fonts.conf. In the first part, it should show this:
-- Font directory list --
Most important directory is /usr/share/fonts. With gnome-font-viewer you can see all installed fonts. For non-professional use, I wouldn't recommend Fonty-Python, but the program font-manager.