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 „:
- „Since” – as a data field
- „Select field” – as a select
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.
3. Check it on list
Last step: check it on entries list.