Two short steps. First the letters, then an estimate of how many common Latin words you already
know. There is no penalty for knowing nothing — that is where most people start with a new branch.
1. Which of these Latin letters can you read?
Tap the ones you can read.
2. Which of these words do you already know?
Tap the ones you know. Guessing is fine — nothing depends on it but the starting point, and you can
correct it as you read.
That is an estimate from a sample, not a measurement. Your first few texts will sharpen it: every
word you tap as known adds to it, and tapping one you had marked as new takes it away.