I need help installing and configuring:
If possible can you summarize this tutorial:
http://mysql-apache-php.com/ffmpeg-install.htm
and explain in depth how to edit the php.ini file.
What Distro are you using? Ubuntu / Debian / Redhat / Centos? Installation of those packages will change dependant on distro and their package managers.
Editing the php.ini is easy, using your favourite editor on your platform, open /etc/php.ini