Entity in SDK

Hi all,

i am trying developing a plugin for DCRM 2011.

i have used this small example to get a skeleton of a plugin -> http://msdn.microsoft.com/en-us/library/gg328263.aspx

And i found on a side (http://msdn.microsoft.com/en-us/library/microsoft.xrm.sdk.iorganizationservice.retrieve.aspx) an example which uses the Entity-Class to do some data-action.

now i need some help. Which kind of data could i set with the Entity-class. How can i spezify / find a custom object?

mfg jonathan günz