Detect the key of your track, and then locate it on this keyboard.
Once you've located the key of your song on the keyboard, count the number of keys it takes to get to the key you want to transpose to. For example, if we want to transpose a track that is in F sharp minor to A minor, we would turn our transpose or key knob to a setting of +3 semitones.
If you're transposing a track that's in the key of B Minor and want to get to C Minor, you would just go up one semitone. Think of the keyboard as repeating on either side and count as normal.