I am creating a Warlock with the pact of the tome and reading the Book of Ancient Secrets invocation I got a little lost. It says:
On your adventures, you can add other ritual spells to your Book of Shadows. When you find such a spell, you can add it to the book if the spell’s level is equal to or less than half your warlock level (rounded up) and if you can spare the time to transcribe the spell. For each level of the spell, the transcription process takes 2 hours and costs 50 gp for the rare inks needed to inscribe it.
I am new to D&D so the concept of finding a new spell isn't very clear to me. Can someone please explain how could I learn new rituals with my warlock?