Can anybody tell me from where I can learn all auto Cad commands with full description and illustrations so that I can understand easily...Thank you..http://www.futechmachines.com

You can try the Command Reference at the "F1" key.



 
A full list of all AutoCAD commands (incl. undocumented commands) - but only with a short description - can be found here:
 
www.cadforum.cz/commands

I would suggest the AutoCAD Bible.  You can order it from Amazon.comhttp://www.amazon.com/AutoCAD-2010-LT-Bible/dp/0470436409/ref=sr_1_1?ie=UTF8&s=books&qid=1277078603&sr=1-1It is a full resource for all things AutoCAD.  It comes with a CD version of the book for easy searches.  It is very comprehensive and detailed.  There is a version of every release of AutoCAD since r14 I think.  The version for AutoCAD 2011 should be out very soon.