I just had this question and thought I would write up a quick post about it, in case anyone else is wondering how to do this. There are so many awesome fonts, but it's hard to figure out where to install them on your computer once they've been downloaded. I tinkered around with this last year and figured it out (yay!) and was so happy I did - it's so fun to use different fonts in your newsletters, worksheets, etc.
I found this great, straight forward tutorial online at FontSpring. It lists the steps and has a short video. This should help you install fonts, but if you have any trouble, let me know and I'm happy to help. Remember to close all applications first - the fonts won't install until you restart the applications you are trying to use them on. Click the image below to view the instructions.