Hi,
i am beginner to developer studio tool. I am using Open_AT_Application_Framework_v2-51_Full_Installer downloaded from sierra site.
I have been used sample application from the Developer studio. In i2c application you are using AT+READ,AT+WRITE,AT+SETMODE like that at commands. In the at firmware guide ,wip at guide the commands are not avilable.Where can i able to see those type of commands or these are created by user? can you explain me
Which sample, exactly 
These are Custom commands created by the application.
They are described in the Documentation (HTML file) for the sample.
Yes - see above!
I am using sample projects given in Devstudio, New-> openATproject->New open AT project->Target platform configuration->Sample selection->externalstorageI2C
In this sample lot of ADL functions like adl_atCmdSubscribe();adl_InitGetType ();adl_atSendStdResponse (); etc, are used in which file shall i get definition of these function? or else those functions arepredefined.
All ADL functions, and associated data types, etc, are documented in the ADL User Guide.
Also in the Open-AT tutorial book.