what is the best site to make instrumental tracks for utau vocals?

HIII UTAU-ERs, i'm currently getting into making songs with utau, teto in particular. BUT i can't figure out which site is best to compose songs with her, because normally i use garage band but it just doesn't work on my computer. Is there any music making sites that work well with utaus?? bc im SOOO lost (any recomendations are welcome!)