Theory is the grammar. This is where you collect the things you actually say. Write down a lick you love, name the key and the mode you hear it in, add the chords — then drill it around the circle of fifths and through every mode, the way a phrase is meant to be practiced.
Click the staff to drop a note at that pitch — it snaps to the scale, then nudge it with ♭/♮/♯. Click an existing note to select it. The chips under the staff show the scale degrees — that's what gets stored, so every key and mode comes for free.
Change the Key to hear the same shape somewhere else; change the Mode to recolour it over the same chords — Ionian to Dorian, and so on. That's the whole point of practicing a phrase.