Hello @EllenA83 ,
When you create any campaign like an email, event, landing page, etc. you are given a unique link. This unique link can be shared across various media, including in other emails, on social media, in text messages, and so on.
With events, the standard "share url" we provide is a direct link to the event's Landing Page (or to the Registration form if the landing page is unchecked). You can potentially utilize the emails from within the event builder. These use an older email system, but are good for tracking who has already been sent the email for the sake of sending follow-ups to people who haven't either declined or registered.
However you can also utilize the regular emails created from within the Campaigns tab > Create. Here you can insert a normal button , bit of text, an image, etc., and use the event's "share url" as the hyperlink.