Adding metadata to a FLAC file

I have successfully downloaded the FLAC file of a Mark Knopfler concert, but it does not contain the metadata to enable me to find the file to stream it through my Linn Klimax Digital Streamer using Linn Kazoo and MinimServer. I store my music files on a QNAP NAS. I know that the file is OK, I have copied it onto a Fiio mobile device which I use in my car, and I can play the tracks although the file is identified there as "Unknown File".
I have used MP3Tag in the past to re-tag files where the metadata needs reorganising , but always from published sources (ripped cds, downloads of files with metadata). It's a long time since I used MP3Tag, and now I am using a MacBook so am trying to make MP3Tag work with macOS Mojave 10.14.6.
I have managed to successfully (I think) install Mp3tagv.2.97 from the site, and have used the Change dîrectory command to populate the right-hand side (Filename, Path) with the list of tracks from the FLAC file saved on the MacBook.
But I do not know how to find/create the necessary metadata, including cover art, to populate the left-hand side. My memory tells me that simply typing in the Title, etc will not work.
For some reason I am unable to access the "Help" function: I receive the message "Mp3tag was not able to display the help file in your standard web browser" (Firefox). Does that indicate that Mp3tag is not properly installed on my machine?
I would be very grateful if someone can help me.

Many thanks, Gonzalez

If you want to have a look at the help, you can also use the online version:
http://help.mp3tag.de/
and there perhaps esp.
http://help.mp3tag.de/start_firststeps.html

Thanks for that, ohrenkino, very helpful. I have made a little progress. By adding a cover art image to the FLAC file and changing the directory in Mp3tag to the enhanced file, and then using a tag to populate the Title column with the track list, I have managed to save a file on the NAS which Linn Kazoo identifies as "No Album" but with the track listing and cover image by each track. But I have not yet managed to copy the cover image to the File level, and I have not managed to see how to tag an album title to get rid of the "No Album" identifier.

So if anyone can give me a bit more help, I will be very pleased indeed!

Gonzalez

Select all the files that should get the same data for a field, e.g. ALBUMARTIST, ARTIST, ALBUM, YEAR
Enter the data in the tag panel (window part on the left) in the corresponding fields
Press Ctrl-S to save the modification.
You may now use the track numbering wizard to get the track number.
You would have to enter the titles one by one, though. If you do that in the files list, then the changes are saved as soon as you leave the table cell.

Dear ohrenkino - you are a star! I have done what you suggested and got it first time. I now have the file identified by Linn Kazoo, with the cover art in place. Brilliant. I really an grateful for your help and expertise!!

Gonzalez