"Sandbox"

Hello

I am very inexperienced in html, php, and css. However, I do have a working knowledge and I have been working on my site. I do have an IT guy and he is great…but –

I want to create a sandbox on my home computer. The IT guy did the work on the original website, so the downloaded files from WordPress site on his home computer – not mine. If used an FTP Client program like Filezilla, couldn’t I download the files necessary to create a private copy of my website on my home computer so I could play around with the site and then after I made changes I like and work, upload the code to the live version? Or MUST I have the originally downloaded files to make the sandbox?

Lastly, anyone have any opinion on Filezilla they would like to share with me?

Thanks in advance for any incite you can give me.

Nick