Datagrids: How to change Column order?

Question

I am new here so forgive me if I am asking a question that has be previously answered. I have program which uses an ArrayList of Objects as its datasource; however, I can find no way to change the order in which the columns are displayed. Neither can I figure out why the DataGrid is displaying the columns in the order it chooses. I read something about using the TableStyles collection and setting the mapping name; however, nothing comes up in the mapping name box of the collection. I am really lost here and frustrated--this seems like it should be so basic. Please help. Thanks, Chris B