How To Add A Host To A Facebook Event

1. From your Feed, click Events in the left menu. You may have to click See More first.

2. Below Your Upcoming Events, select the event, then click Edit.

3. Below Additional Details, click Event Settings.

4. Type a friend's name in the box and select them.

5. Click Save, then click Update.

Resources: https://www.facebook.com/help/215235325174804