Dipole in an Uniform Electric Field concept?

Homework Statement

Dipole in an Uniform Electric Field:
torque is calculated about the position of either charge has the magnitude FLsin(x) = qELsin(x) = pEsin(x). The direction of the torque vector is into the paper such that it tends to rotate the dipole moment vector p so it aligns with the direction of E. The torque can be expressed most concisely as the cross product: T = p x E

I don't know why the magnitude is F * L sin(x) or why qE turns into pE. And I don't understand what the concept iit s trying to tell me. It would also be helpful if someone could explain the hand thing for torque. I understand most of the stuff about torque but not the hand thing.

Homework Equations

x = theta
L = distance between charges in dipole
p = vector of the dipole movement that points from negtive charge to positive.
p =q*L