Congrats on getting started!
All of this is just my personal suggestion, and everyone does this differently. Do what’s right for you!
Assuming you want to learn the Tsugaru style, I’d strongly recommend buying Kyle’s book, “Shamisen of Japan.”
That way you can learn Rokudan (a piece containing a lot of the techniques you’ll want to write your own Jongara Bushi) note for note, read detailed explanations of important techniques, and build up nice repertoire of songs.
Once you have that and get started, if you have any trouble with any of the songs, get the lesson for that song on the schoolhouse and use them together.
Once you feel ready for making your own Jongara Bushi, I’d recommend the Nitta Phrasebook on the schoolhouse.
Then, maybe pick up some lessons that aren’t in the book, pick up The Nitta-Ryu book, or even search around online for Oyama Ryu or Fujimoto Ryu books to expand your repertoire even further.
Best of luck!