where I can get placed after learning autocad
Hello aspirant,
Knowing AutoCAD alone does not qualify someone for a job. What gets you a job is your engineering education and experience. A mechanical engineer with several years of machine design experience can use AutoCAD to take a rough sketch and create detailed drawings of all the parts with all the necessary views and sections. He or she could properly specify all the standard components like fasteners, bearings etc. as well as manufacturing tolerances to get the proper fit between parts.
CAD is only a tool used by engineers and designers to do their work. Like any tool, your ability to do a job depends on what you can do with it.