Hi. I'm new in the HA environment.
How to install a dashboard downloaded from GitHub?
#Install dashboard
light nacelle
Here is this dashboard https://github.com/arsaboo/homeassistant-config
karmic salmon
For the simplest answer: you don't/can't.
The longer answer is more complicated. That user's dashboard is specific to their configuration. More specifically, the entities and files on their system. In just the first 31 lines of their dashboard (located in the ui-lovelace.yaml), I count seven entities/files that are specific to them. You could copy/paste it into a new dashboard, but you're going to get a ton of errors and have to go through and correct each one.
Why is it posted then? Because it is good reference material. I have my dashboards posted on my Github but I know that they won't work for anyone else. But, I do refer to them when answering questions and mentioning how I do different things on the dashboard.
Another thing to consider is how old that information is. Most of the files on there are between 4 to 9 years old. A lot has changed since then. Still good reference material but may not be guaranteed to work.