Few simple steps
First need to go into MS Visual Studio Tools (Usually under Installed version of Visual Studio and then folder)
Open Developer Command Prompt for VS2013 or whatever version you are using
Once opened, change directory to where CrmSvcUtil is (usually in CRM SDK > bin folder) i.e. cd MyDir/sdk/bin
then use sample script below and change values accordingly
CrmSvcUtil.exe /url:https://myorg.abc.com/XRMServices/2011/Organization.svc /out:C:mydirectory\MyEntities.cs /username:rokhri\abcdef /password:ghijkl
Run it and will create a new class with the name of MyEntites.cs in specified directory which in our case is MyDirectory in C drive