You can activate the ILS by first going to the menu of your destination airport. Once there, tap on “runways,” select your desired runway, and click NAV 1. When near the airport, the ILS glide will show right next to the altitude indicator. To turn on the localizer, go to the NAV menu and activate NAV 1. The compass will show a green line, which is the localizer.
I think this person is confused about the existence of ATC as they are on solo mode. Not necessarily how to deal with ATC.
Regarding the topic,
Solo mode does not have ATC, only multiplayer. Expert Server is the serious server, and you should follow all ATC instructions. Training Server is, in fact, a training environment. It is recommended that you follow ATC instructions there as well. However, level 2 and 3 violations are not enforced on training.
Watch the video Thunderbolt posted above for a tutorial on how to fly an ILS approach.