After purchasing a domain name from us, you can edit your DNS configuration for your server through the billing portal itself. An "A name" record is simply a DNS record that allows you to forward a subdomain of your domain to a specific IP. Uses of it could extend to things like adding a domain IP to your Minecraft server (allowing you to join your server using just a subdomain instead of an IP) or pointing a subdomain of your domain to your web hosting service (making sure it is setup to accept that subdomain first).
First, login to the billing panel at https://www.beastnode.com/portal
Once logged in navigate to Domains > My Domains
From there, click "Manage Domain" for the domain you wish to edit
On the management page for your domain, click on Management Tools > Manage DNS
Now you are ready to edit your DNS records.
Under "Host Name" enter what you want your subdomain to be. If you want your subdomain to be "play.mydomain.com" then simply enter "play" into that box. If you want to set the A record for your actual domain itself (mydomain.com), then enter "@" for the host name box. A wildcard entry is also possible with the host name "*" (usually there by default). This wildcard entry allows you to basically make any subdomain A record to point to the IP you set it to (even if the DNS record doesn't exist).
For "Record Type" make sure "A (Address)" is selected
In the "Address" box, enter the IP of the server you want to point it to - do not include any port numbers of any kind as A name records do not support them
- Note: If you intend to use it for a Minecraft server, it will only work if you have the 25565 (dedicated IP) port.
Once done, just click "Save Changes" to save everything. As with all DNS changes, it can take anywhere from a few hours up to 48 hours before the changes propagate around the web.