Adding a custom field correctly

Hi,

I am trying to add a field, “Country of Origin”, that would work similar to Categories:
-Countries can be added, similar to the Add New Feature of Categories
-When creating an event, you can select a drop-down of previously entered Countries
-When viewing an event page, the Country of Origin would display

I used this tutorial: http://wp-events-plugin.com/tutorials/creating-a-events-manager-add-on-a-complete-walkthrough/

I was able to add a section that would allow me to add a Country of Origin field. However, when I added the code here: http://wp-events-plugin.com/tutorials/creating-custom-permalinks-in-wordpress/
I received syntax errors from this line:
$events_slug = $events_page->post_name;
Without the code from this page, it seemed to work, but it doesn’t function like Categories (drop-down box when creating an event, or displaying on an event page)

Am I doing this correctly, or is there a better way?

Thanks!

https://ww.wp.xz.cn/plugins/events-manager/