are you using Windows? If yes there are couple of things you can do to add fonts.
The way to permanently add fonts to your system so they will always be available is to copy them into the Fonts folder inside your Windows folder.
I like to have many, many, many fonts available. But this can slow down some applications like Photoshop. The way around this is to keep the fonts in a separate folder. I open the one I want to use by double clicking it. When it opens in the font viewer (the repeating "lazy dog" sentence in various sizes), it is now available to be used by any other software I open afterwards...just make sure to leave the font viewer open but minimized. DONT CLOSE IT OR THE FONT IS NO LONGER AVAILABLE TO THE OTHER APPLICATIONS. I put that in bold because I see people (over and over) close the viewer instead of minimizing it, then wonder why it's not working.