You can only view and sign-up for an event if you are on the invite list of the event.
To see what events you have been invited to sign-up for, click on the Events tab, and then Sign-up Events subtab.
If you are on the invite list you will receive an invitation email about the event, unless the creator purposefully elected not to send an invite email. You can click on the Sign Up button in the email to be directed to the event's sign-up list.
Calendar and Dashboard
If your school has the Dashboard and Calendar modules, and the creator of the event elected to publish the event on the calendar, then the event will appear on your calendar and on your upcoming events in the Dashboard.