There are typically 2 levels that make up the Conferences i/o product -- The Event, and the Sessions within an event. While it's also possible to have an arrangement where there's just a single session, let's look at the common example where an event has multiple sessions.
For Events With Multiple Sessions
If your Conferences i/o has been configured to support multiple sessions, your attendees will then typically see a schedule (or listing) of all of the sessions, in date order, when they navigate to your dedicated URL (for example: acme.cnf.io). This "home page" therefore serves as the listing of your sessions which users can then pick from to interact with.
Attendees will simply click on the session that they'd like to join from the home page. Once they have completed their interaction with that particular session, they must return to the home page to choose a different session to interact with. They can do so by either clicking the top logo, or by choosing Home from the menu button.
For Events With Only One Session
If your Conferences i/o has been configured under the "Single Session" structure, users won't see a list of different sessions to pick from. Instead, they'll typically see the Social Q&A feature and any unlocked poll questions. But there won't be a list or schedule of sessions to pick from. In other words, your attendees won't be required to click on a particular session within a schedule.
When you have a simple event or a one-day event need, this is a common structure which tends to make the user experience easier or simpler for attendees.
Your sales contact or your customer success manager will advise you on the best setup or structure, based on your specific needs.