Creating an event on Facebook is a great way to send out invitations to multiple people, as well as keep track of events.
Creating an event is easy. To start, access the Events applications.

Next, click on the gray 'Create new event' button.
Fill in the required fields, and click next.
In the next screen you can add additional details, including a picture, type of event, and the description. Although you may skip this step it is recommended you fill in some details so everyone can be clear on what is happening.

Click Save, and your event is now live!
You may invite friends to the event if you choose to do so, which is 'Step 3' in the above process.
Going back to your Events page, you will now see your event there.