The component of torque of a force F acting at a point r is equal to the vector product of the vector r and the force.
Mx=y Fz -z Fy,
My=z Fx -x Fz,
Mz=x Fy -y Fx.
You can also decide the sign from the direction of rotation the force would cause along an axis. Seeing from the positive x, y, or z axis, the moment is positive if it rotates anti-clockwise, and negative, if the rotation is clockwise.