New user looking for suggestions on DNS setup

I just installed the 17.2.0 NC on raspberry pi.
After 2 days of tweaking I got it to work mostly.
I googled and saw there’s an option to configure in the app but can’t seem to find it.
Also, I also read ‘TUI’ 'WebUI" references online but not sure what it means.
Any help is appreciated.

If you would have used the search function of this forum you had found, e.g. this DynDNS related postings:

I found this but did not see anything specifically for DNS, than now I see it’s under “docker”.