Connect switches together with trunk to allow multiple vlan's across

My experience with basic TCP/IP and switches is good.
But as soon as you start trying to explain vlans, tagged ports untagged, trunks and lags, I quickly lose focus (mostly because one thing references another that references the first)

So.
I have a Unifi USG.
It's plugged into a HP 1820-8G POE+
Which plugs into a Dell 2816 and a Dlink 1100-08p
I have a Unifi Access point plugged into the Dlink 1100.
Servers are plugged into the Dell 2816.
All switches are managed.
I want to be able to vlan a VPN connection to one of the servers, and Vlan a SSID on the AP to the internet without giving access to anything else.

How do I trunk and vlan this stuff. Everything is setup with no vlans or trunks currently.?
Explain it like I'm 5 please.