Hi Neda,
BLOT: It's not an easy conversion. Use specialized toolboxes for EEG source localization.
I'm not a GraphVar user but your question can be thought of as a generic question on Neuroscience, especially EEG. In the EEG world, what you asked for is called "Source Analysis" or "Source Localization". It's not an easy problem because you need to calculate many unknowns out of small known variables. In other words, you only have information from 64 channels but the brain is composed of trillions of cells, which is hard to solve. (FYI, some people call such a problem as "inverse problem.")
Also, I'm not sure if GraphVar Toolbox provides any functionalities for source localization. I shortly breezed over the article for GraphVar 2.0 and it seems like it's more likely related to graph analysis.
My personal recommendation for EEG source localization is FieldTrip and Brainstorm which are ones that I used when I was in grad school. You can find detailed introduction how different source localization techniques work and how to implement them for your dataset with their toolboxes.
Hope this helps
