Child Theme Question

[travelin cat]

I have recently been creating a few sites in WordPress and have been modifying the style.css, header.php and footer.php. My question is, can I move the already modified docs in to a child theme so that when I have to update the theme, my changes are preserved in the child theme?

Is it as simple as creating a directory and taking the existing docs (I understand about modifying the header in the css file), placing them in the theme directory and then just continue to modify the child theme as needed further without affecting the layout of the site?

[lorax]

I believe it is but as usual, the devil is in the details. I've been using Thesis mostly which doesn't rely on a child theme so I'm not absolutely sure. In about 4 months I'll be up to my keister in a child theme but right now the best I can offer is less than definitive.