Simply I need to calculate the torque required to move this solar tracker in the attachment assuming that i know every part's weight. What is the criteria should i follow?

Estimates of friction at all joints, Rate of acceleration desired as it starts up. What loads does wind have on the structure? Hint start with a free body diagram...……..

When i selecting a motor I'm checking all the moments in the system @ each angle and literally build the movement profile. After that its easy to understand what is the required "continues moment and what is the peak moment. Mt=F*L for movement. Mt= I[Kg*m^2] × alfa[rad/sec^2].for acceleration. Here is a good guide for motor selecting: https://www.machinedesign.com/motors-drives/article/21831643/how-to-pick-motors-for-linear-motion. Try to think about direct drive instead of spour gear Good luck

Attached is a drawing of a machine that produces 118,428 foot pounds of force traveling at a speed of three (3) feet per second. How can I convert this to torque and then to potential electric output?

Units of force are pounds or Newtons. Foot-lbs are units of Torque or energy, not force. Clarify what you have.