Need help to back-up my site

I have have hired a freelancer to do some coding on my site. After spending about $800 I am starting to have suspicions about his work. Before I give him the password to implement his code I would like to have a back-up of my site on my hard drive or somewhere.
I do not have technical talent and question doing this myself.
Is it easy?
Should I hire someone?

Thank you, Andy