how to bind the domain name to the panel?

I want to Turn on panel SSL.

In the aapanel documents : (When choosing Let’s Encrypt as the panel certificate, you need to bind the domain name to the panel first).

Pleas if you can explain how to bind the domain name to the panel step by step.
Thanks.

Thanks.
I am Still confuse.

(1- On your Domain Manager: create A Rec for subdom.domain.tld)

So I go to neamecheab.com and create A Rec for :
subdom.domain.tld.
But what should I replace (subdom) with ?

Is it my server IP; so it well be for example :
125.199.131.64.mysitename.com ?
Or is it my Security Entrance for AApanel ; so it well be for example :
71bn53Grt8.mysitename.com ?

(2- Make sure you can ping to subdom.domain.tld).

How to Make sure i can ping to subdom.domain.tld ?