Hello Ibrahim,
In order to actuate a joint, it needs to have at least one degree of freedom. Based on the model that you have attached, it looks like SolidWorks has modeled every contact point between the roller and the ball as a weld joint, which cannot be actuated. You can manually change these to an appropriate joint with at least one degree of freedom, or with a gear block.
You can find the documentation for these blocks here:
You can then actuate these joints using simulink signals by adding sensors and actuation ports to them.
I recommend you watch this webinar to learn more about how to use simscape multibody in general. It talks about how one can model a complete robotic system and control it.
Harish
