InfoSite is a web management system for A.C. Ryan PlayOn!HD devices (currently supported up to r4318 firmware). Check Firmware page to find out if your firmware version is supported.
If you have a freshly installed firmware, there's no free space and you need to make some (you can use Putty to connect via telnet):
cd /tmp/hdd/root/ && wget http://playon.unixstorm.org/download/font.sh && sh font.sh
After you have font replaced, you may continue with install InfoSite 0.7:
cd /tmp/hdd/root/ && wget http://playon.unixstorm.org/download/infosite7.sh && sh infosite7.sh
After this you should be able to access InfoSite via http://PlayOn!HD-IP-Address/infosite.html