As the host of a Facebook event, you can edit the event's details and invite people to attend it. You can also add other hosts. Use the Edit button on the event page to add hosts. You can only add hosts to an event using the Facebook website. The official Facebook app for mobile devices does not offer this functionality, as of publication.
Add Hosts to an Event Using the Facebook Website
Step 1: Click Events on the menu along the left of Facebook.
Step 2: Select the event to which you want to add a host. If you are attending multiple events, click the Hosting tab to just display events you are hosting.
Step 3: Click the Edit button located near the top-right corner of the page.
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Step 4: Type the name of the person you want to add in the Hosts field, select the person's name when it appears on the pop-up and then click Save to finish adding the host.
Use the Edit button on the event page to modify other event details as well. You can change the event name, description, location and time. You can also update the level of privacy using the Privacy pull-down menu at the bottom of the dialog. Privacy options include Public, Open Invite, Guests and Friends and Invite Only.