Controlling RF sockets with Hassio

Hi All. Have install Hassio image to RPi3, added MQTT, SSH, Samba, and everything is fine. I.m able to control two hacked sonoff basic switches. what I want to do now is control some RF sockets. Found a guide on the web regarding installing add-on for this by “pantomax”, but this is my 1st question How do I install the add on?. Found this on github “https://github.com/pantomax/hassio-addons/tree/master/rpi-rf-receiver” where it says install addon - takes 5 to 10mins, but how do I do this please. Running Hassio, Home Assistant 0.73.1. Most probably an easy answer but cant find it. Do I in my web interface - click on hassio add-ons?

Have a look here…