Long Shamisen Song
Epic Shamisen Song, Nagauta
A long shamisen song is a long shamisen song! They're also called nagauta, and they're usually pretty epic too.
ながうた
The readings for this word are both kun'yomi readings. You learned them when you learned the kanji, so you should be able to read this on your own.
長唄教室に通い始めました。
I started to go to the nagauta class.