Lower Traps (Prone Y)

So i need a bit of help with strengthening the lower traps, ive been told to do prone y's and cant figure out how to use the lower trapezius. Do i retract and depress the scapular and then raise my arms? Do i retract and depress as i lift my arm? and also do i lead with my arms or raise the arm purely using the scapular? Any tips will be greatly appreciated.

Thank you

I would suggest retracting your scapulae first - drawing your shoulderblades back and down, as if squeezing a coin between them, then focus on maintaining that position and lifting your arms up.

I like this one, good luck!!!13.3 Scapular Rotators Lower Trapezius Strengthening - YouTube