As soon as you have completed setting up libreevent, there are some things you want to change on the admin panel. First off, you want to create an event location and an event. Secondly, you may want to customize the start page, which you can do in the pages settings on the admin panel. You may find documentation for this here. Lastly, you need to configure and set up a payment gateway in order for you to accept payments. Additionally, have a look around on the admin panel to change settings where you see fit.