For Syncthing? All you do is point it to the folder where it is (or where you want it to be if it’s not on the device yet). Then you tell it that you want to send and receive changes for that folder, and repeat this for all devices you want synched. It’s very simple. Just play with it and you should be able to get it working.

One thing to note is it needs to be running to synch obviously, so if it hasn’t been running don’t expect your database to be updated.