Creating a sub graph of a graph with Cypher

I have made a graph of all the processes and now I want to realise sub graphes which can be based on a relationship, processes linked to a typical process, and so on.
But the point is that I dont know ho to select simply into a graph
Thank a lot

Hi, Gerard.
If your question is still actual, can you build an example of graph and explain again you problem: what query expect to do. I dont understand it... but ready to help.