Hello @DonnaP144 ,
You'd need to email your contacts, either using the older email builder that's connected to the event you made or the normal email builder. Using the event's email builder will allow you a few extra capabilities that are directly connected with the event, such as the ability to email registrants or non-respondents directly without additional manual list sorting.
I'd recommend checking out articles on the topic for instructions, visual guides, and additional info.
See also:
Editing event emails
Copying event emails
Scheduling event emails
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