How to create a “child theme” on DW Simplex?

Do I need to create a “child them” when majorly modifying the original SIMPLEX them?

I received lots of help in modifying the Simplex them for my use (thanks so much!). That said, I recently came across a posting on WP regarding creating a “child them” for major “theme” customization so that in the event the original is updated I don’t lose all the customization (http://codex.wordpress.org/Child_Themes).

Is this something I should do at this point? If so, can you walk me through how to do this considering there are lots of files I modified in the original them (removing blocks, altering colors, etc…). If I don’t need to create a child please let me know that as well. I am not a developer, so need details on what I should or should not do.

Thanks so much for your help.