Testing Area Within ModX Evo

Hi, I am new to Modx having only worked with Wordpress before. I want to make major changes ModX site but am afraid of doing anything drastic as this is a professional organisation website. What I would like to do is create some kind of practice area where I can play about with different templates without affecting the live site. I would be super appreciative if someone could point me towards a guide to doing this or walk me through it in baby steps.

Cheers,
Jon