Text analysis of single words

Hi everyone. I am struggling with a text analysis. I've done all the process in order to transform and tokenize all my document. But now I need to find what are the words "related" to other specific words. For example, I want to find, in all my document, all the words which come after the word "I", "we" and "you".

I tried many different operators but I can't come up with a solution. 

Thank for your help