You must be using MythTV .25+
This page is for Debian based systems. Specifically it was written and tested on Ubuntu 12.04 and 14.04.
Add to /etc/apt/sources.list
deb http://repo.mobilemyth.net/ repository/
sudo apt-get update
sudo apt-get install mobilemyth
Note there is currently a dependency conflict on debian.
OLD MANUAL METHOD
This guide is assuming you already have apache installed and you will place the website in the folder /var/www/mobilemyth.
sudo apt-get install unzip mono-runtime libmono-microsoft-visualbasic10.0-cil libapache2-mod-mono mono-apache-server4
wget -O latest.zip https://github.com/jheizer/MobileMyth/blob/master/release/latest.zip?raw=true
sudo unzip latest.zip -d /var/www/
sudo chown www-data:www-data /var/www/mobilemyth -R
sudo mv mobilemyth-apache-config /etc/apache2/sites-available/mobilemyth
sudo a2ensite mobilemyth
sudo service apache2 restart
If you want to be able to control frontends on your network you must edit /var/www/mobilemyth/App_Data/frontends.xml and add your FEs.
Now browser to http://YourServer/mobilemyth to enter the settings and Enojy!
If you are having problems getting the home page to setup after filling in the settings browser to http://YourServer/mobilemyth/admin/default.aspx and double check your backend settings.