Answer as a tutorial.
The tutorial was created sometime back for SpaceClaim 2012 version and should be a good start for newer versions as well. The tutorial has been broken up into three videos below.
1) How to model parts in SpaceClaim for an assembly, from scratch? An example of a slider crank is taken.
Video is at https://www.youtube.com/watch?v=hqJA6KfDBfY
2) How to define Assembly Conditions/Constraints between the parts?
Video is at https://www.youtube.com/watch?v=Id-RNuxgYKA
3) Motion and Dynamic Simulation of SpaceClaim assembly using SC-motion.
Video is at https://www.youtube.com/watch?v=8k-e9UGil1E
A detailed tutorial on the above is also present at AR-CAD Blog http://blog.ar-cad.com/2012/06/19/assembly-modeling-and-motion-simulation-in-spaceclaim/
SC-Motion is a motion and dynamic simulation addin for SpaceClaim. SC-Motion 2012 (version) is available for 99 USD. For more details, please visit http://www.ar-cad.com/sc-motion/index.html