Once a schedule has been published, when viewing a specific opportunity in the Opportunities pane there are two ways to invite volunteers to sign up.
You can (1) select "Copy link" to share the link yourself
Or (2) select "Compose email" to use our built-in emailer to send this schedule to your existing volunteers.
(Note that if a schedule is "Protected", only people who are already in your database as volunteers will be able to access that schedule.)