How to run Madgraph to calculate Feynmann Diagram

[zhangyang]

Hello,
Now I am studying some software to analyze the scattering process,but when I download the Madgraph and Python,I can't enter the interface,now I tell you my operation,could you tell me where I am wrong?
First,open Python,File open (madgraph tutorial text).But how could I operate next?
When I input "./bin/mg5_aMC" in the Python interface and Enter,result in an error.How to correct?
Thank you very much.

 

[zhangyang]

Now,I try to use the web edition on http://madgraph.hep.uiuc.edu/
Input "e+ e->a a" which express positive and minus electrons convert into two photons,"submit",but why cann't I get a correct result on Feynman diagram and cross section?