First, the DNS editor must be enabled by clicking on [set preferences].
The following are sample entries:
Add DNS record: [A] for domain [foo] pointing to 22.214.171.124
This creates a new entry for foo.your.site.name pointing to the 126.96.36.199 ip address.
Add DNS record: [MX] for domain  pointing to smtp.externalemailserver.com
By leaving the domain blank, this disables memebot's email reroute and causes all mail for your.site.name to be received at an external mailserver.
Add DNS record: [NS] for domain [sub] pointing to ns5.someothernameserver.com
This delegates a subdomain sub.your.site.name to an external nameserver.