How to Draft the Casting model in understandable way ?

Ramesh, What draft angle does the part require? It would be best if someone with SolidWorks 2013 added the draft. Otherwise, you'll only be able to import a "dumb model".

Take a loot at the attached image showing a section of your model. You'll want to add a fillet to the inside. Right now the model has almost no thickness and won't work well if it is produced.

Ramesh, you should check the model, take a look at the attached image markded below area