copy fonts to one of these folders :
$Home/.fonts/
$HOME/.local/share/fonts/
/usr/share/fonts
/usr/local/share/fonts/truetype
then run this command or restart your system :
sudo fc-cache -fv
References :
http://www.wikihow.com/Install-TrueType-Fonts-on-Ubuntu
http://askubuntu.com/questions/533462/how-do-i-uninstall-a-font-installed-using-gnome-font-viewer
https://askubuntu.com/questions/191778/how-to-install-many-font-files-quickly-and-easily