You're just a little bit lost, and doing no harm to your computer, so far.
Please don't use root, it's just asking for trouble if you don't know exactly what you're doing.
I recommend using Syncthing-GTK: https://github.com/syncthing/syncthing-gtk This way you can use Syncthing on your desktop and it will install and update Syncthing Core for you, you don't have to install it manually if you're using Syncthing-GTK.
Let me know if you need help installing Syncthing-GTK.
However if you want to install syncthing manually, follow the steps below.
Please run the following command in Terminal for step 1 of install Syncthing:
curl -s https://syncthing.net/release-key.txt | sudo apt-key add -
You'll notice the
sudo has been added before
apt-key. Run the above command in Terminal and type in your password. This will add the release key to your computer.
Then run the following commands in Terminal for step 2 of install Syncthing:
echo "deb http://apt.syncthing.net/ syncthing release" >/tmp/syncthing.list
sudo cp /tmp/syncthing.list /etc/apt/sources.list.d/
The above 2 commands add the syncthing repository so that your computer knows where to get Syncthing from.
Now update apt:
sudo apt-get update
And then install syncthing:
sudo apt-get install syncthing
And you're done.
Run syncthing from command line
syncthing or go to
/usr/bin in Files browser and double click
syncthing to launch.
http://127.0.0.1:8384 in your web browser to see the Syncthing dashboard.
You'll need to setup a script to auto-start Syncthing when you turn on your computer. However, Syncthing-GTK has all these settings and more in a very nice user interface, so I recommend using it instead.