How does SKM Software calculate the bolted fault current for arc flash studies? What are the steps of calculating short circuit current by using comprehensive short circuit studies?

I would suggest that you read the user guide SKMInclude_PTW Userguide.pdf and tutorial SKMInclude_PTW Tutorial.pdf. There is a ton of information that will educate you on how the calculations are done. If you have a valid Maintenance Agreement and are up to date with your maintenance fees, then you can go to their website and down load these two documents.