Your event will be automatically displayed on the news feed of all fans of your page. 

If you want to promote an event through advertising, you will find all the necessary information here and here

If you want to invite members , you can do so from the "your events" menu on the top banner of your page.  

By clicking on this tab, you will see a list of your current events. 

Click on an event to see the "invite" button, you can then send an invitation to the fans of your page.

Web version : 

Mobile version :