what is the best way to learn how to find angular acceleration?

Answer 1

Parallel to how you learned to find linear acceleration. Learn the equations
wf = wo + alpha*t
theta = (wo+wf)*t / 2
theta = wo*t + (1/2)*alpha*t^2
wf^2 = wo^2 + 2*alpha*theta
and
T = I*alpha (the equivalent of F=ma)

Then choose the equation that involves what you know and what you need to know.