Add custom column to custom post type overview in backend

I have a custom post type called events. In the backend/administration I can list all these custom post types, that is, events:

As you can see, there are three columns in this overview: Title, Tags, and Date. Each of these events has a custom field named eventDate.

My question now is, how can I add a sortable eventDate column to the events overview (pictured above)?

Okay, I found an answer myself. To help people who will read this in future, this is what I did:

1) This explains how to add a column: http://www.deluxeblogtips.com/add-custom-column/

2) This explains how to add a sortable column: https://wordpress.org/support/topic/admin-column-sorting/