Hi,
what are you trying to achieve? because add torque requires a rigidbody and a good understanding of the physics engine that Unity uses. if it;s aregular object, use the action "rotate", "rotate towards" is more complex and requires a target for this.
so if you simply want a never ending rotation, simply use "rotate" and check everyframe and per seconds as well as the value for which axis you wanto rotate ( put 90 in the y and it will rotate 90 degree per seconds)
Bye,
Jean