This is pretty easy.

All what you need is made those three steps:

1. Add custom fields.

First you must add custom fields to selected post type or custom post type. Then go to Types -> Custom Fields and add a group with few fields. I added CPT “Clan” and group “Clan Data” and two fields “:

  1. “Since” – as a data field
  2. “Select field” – as a select

Custom Fields group with fields

2. Tick selected Custom Field(s).

After you successfully add a custom fields, go to custom post type edit screen and choose which custom fields should be displayed on entry list.

Edit Custom Post screen

3. Check it on list

Last step: check it on entries list.

Custom Post entries list