Margaret, Ellan Vannin is NOT the Manx National Anthem, that is "O Land Of Our Birth.
Ellan Vannin is generally recognized as the Manx National Song.

Bobby Bob and others have given the traditional lyrics from the original poem by Eliza Craven Green but as you asked for the tune sung in the traditional way you can find it with this link:
Ellan Vannin (Including lyrics and chords)

I sing this regularly at my monthly sing-around at the sheltered accommodation at which I live in Port St Mary in the island.