There is power in song, just as there is in prayer. Music, though, doesn’t require one to follow a god to call upon the magics within it, and so there are many schools of both arcanists and mystics who use song, dance, and instruments to cast their spells and rituals.
Spellsinging is an odd school of magic, in that it looks fairly simple and seemingly doesn’t require much in the way of material components or knowledge of arcane symbology. However, it is as much an internal mastery of magic as it is a performance, as a spellsinger lets their own internal wellspring of mana loose into the world, shaped by their performance. A lay person can precisely replicate a spellsinger’s performance, and it still won’t produce any kind of magical effect.
If you wish to play a spellsinger, spend some time coming up with performances for your character’s repertoire. Adapt existing songs to match the effects you want to call forth in your rituals, and come up with a few lines of song to match the Spells you want your character to use that include the relevant Calls. If you’re using a more performance-based form of Spellsinging, then come up with some routines to use in rituals. Have fun, be creative, and don’t be afraid to be ridiculous.