A webinar is online training. The participant does not have to go to any special place. All she needs is an internet connection and the equipment needed for a call (microphone, headphones, or webcam).
The topic for a webinar can be arbitrary: from a lecture on the benefits of a vegetarian diet to the analysis of political intrigue on the eve of the French presidential election. Practically anyone with an audience can host a webinar: just have a webcam and a YouTube account.