> Now I would like to create a big knod which include all these three, sum up the Indegrees and show the edged to the different actors. Can Visone do that or do I need a new .csv file? I found the grouping option bus this is not what I want to use.
Well, the grouping feature would actually allow you to calculate the total indegree easily: Group all concept nodes according to their categories, collapse these groups and then calculate indegrees. This assigns the group's indegree values to the group nodes.
If you don't want to use group nodes, you can also do the following: Navigate to the transformation -> nodes -> merge feature and select "contract nodes". For each category, select the corresponding concept nodes in the network and then click merge. That should merge exactly those nodes you selected and leave the rest of the network untouched. You can also specify there how attributes should be handled when merging nodes this way.
If you also want to merge links afterwards, you can use the transformation -> links -> merge feature.