a font doesn't work on Photoshop, a font works on Windows.
So you need to install the font on Windows, not on Photoshop.
everything's written here : http://www.dafont.com/faq.php#win
you can eve find videos on "how to install fonts on windows" here : http://www.youtube.com/results?search_query=dafont
All times are CET. The time is now 17:09