Unable to get DNS to work

I am new to Linux, and have recently installed Linux Mint Xfce 19.3 on an older laptop. A friend helped me build the Ethernet interface from scratch. Everything was done via the command line. We finally got it to the point where I can ping the router. He added name servers into resolv.conf directly, and everything worked for a short time until after he left, when it no longer worked.

I have tried adding name servers into /etc/resolvconf/resolv.conf.d/tail with no success. My /etc/network/interfaces currently looks like this:

auto lo
iface lo inet static

auto enp8s8
iface enp8s8 inet static
address 192.168.1.200
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 208.18.47.61 208.18.47.62

How do I get DNS to work?