Dear Alfonso, 

I'm trying to compare connectivity within one network between two groups. Going to second-level results and ROI2ROI analysis, I have chosen my between-subject contrast and my between conditions contrast.
However, I am unsure about how to choose the seeds/sources and which contrast to enter. Furthermore, once I click on "graph theory", I'm unsure which regions to select. 
Say I want to compare connectivity within a network consisting of regions A, B, C, and D between my two groups: 

Do I select the sources A, B, C, and D, enter the between-sources contrast "0.2 0.2 0.2 0.2", click on "graph theory", and, under "select network nodes", I again choose the ROIs A, B, C, and D? 

Subsequently, if I find a difference, e.g. in average path length, in one regions, e.g. A: does this mean that between the two groups, within the network A-B-C-D, the region A has a different path length to all other regions?

Thank you very much for your help,
Kind wishes,
Charlotte