In an OTO, you want to drag the offset setting to the start of the silence in a sound, and the cutoff to the end of the silence in the sound. Then, you want to drag the fixed/consonant setting to the end of the consonant, which appears more jagged or thinner compared to the smooth, loud vowel, and drag the preutterance there as well. Drag the overlap anywhere you want, as long as it is less than 1/3 of the way through the note.
If you want a simple but more in depth tutorial, I recommend using Kiyoteru's tutorial in the resources section.