as Tom said above, it is just a matter of having the right files in the right locations. There is no ‘installation’ as such, in the way you would consider installing applications.
One very easy way to do it is to first install (this one is actually an install) the ‘Cloud 9 IDE’ HassIO add-on from the add-on store. This lets you open a second browser window where you can see, edit and add the yaml files very nicely. I use it as my main yaml editor. Once you have this installed it will make setting up the alarm system (and all of your other yaml editing) a lot easier.