Add event custom field

Hi guys,
I’d need to add a custom property for my events.

Can you suggest me a good way to do it?

MetaPost tag or a new table where to do a join query or something else?
Is it possible to add a new column to em_events or I destroy some Events Manager part?
One last question: how can I add this new custom property when I add new event from backend?

Than you very much

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