Answering for others:

Adding a variable in Main.

In the ParameterVarietion experiment window, in the After Simulation Run, including the code:

root.resourcepool.utilization();

You can view the resold with a traceln(root.resourcepool.utilization());

Now, the problem that i have is to graph it in the same window (ParameterVarietion). Does anyone have any ideas?

Dear Alex Popp 

see the following site may be help you

"http://www.anylogic.com/experiment-framework"

Hello Razi, 

it does not help :(, unfortunately. There is no description of 'how to'. I even checked youtube for tutorials. There is also a limited amount of information regarding parameter variation and how to graph (only thing that i found was the 2D Histogram).

I am providing the answer (after long trials and errors).

In Experiment, create a HistogramData

Disable automatic updates

Leave value field empty

In experiment, After Simulation Run, add values: data.add (root.value)

I hope it helps other people as well. 

Alex