How I can add a new column

[nacaruncr]

Well, I explain me better.

In the forum, I want to delete the column "Threads & Posts" and I want to change it for a new column, I want to add it the moderators.
Until there all fine, I did add in this place the moderators, but, up from this, I want to add the word "Moderators" like "Main Category" and "Las Post"

In this pictures I explain me better.

This is default form


And this is the form like I want to have it


I do not know if someone could help me or tell me what I have to do .... please, I've been playing a lot of fun with codes and do not get it yet.