Calling Events from a different class

Question

Hi,

i need a solution for a problem where I want to raise an event from
a complete different Class. Here my Example.

I have class1 where I want to invoke an Event.
Then I have a 2nd Class which will be executed in a different Thread.
Because I need to check a message queue. If there is something in the
messagequeue which I need I want to invoke an Event in the Class 1.

How can that be done. Please post just a small hello world example.
Thanks.