You'd probably be best to read up on css a little... here's the gist
To edit some css, you never touch the parent (2011) stylesheet-or any part of the theme. That is the point of your shild theme.
If you wish to edit something from the parent style.css, you copy that particular block to the child theme, and make your edits there.
Using the @import rule, the parent theme loads first, and then your child. So your revised style in your child theme loads over the parent so to speak, and your changes are used.
That's why we don't want to put unchanged rules into the child sheet - we just load unnecessary code, and increase the potential for conflicts. The child theme is only for edits, or brand new css. On voodooPress for instance, I have a 2011 child theme, and my style.css is quite short.
The order of the code going into your theme often isn't important (for a basic child theme with minor revs), but it can be (the more complicated the changes become). CSS stands for cascading stylesheet, and the rules cascade so to speak - the rules take effectin order, so rules further down the stylesheet can overwrite ones further up the sheet.
So you can group like sections of css together - for instance styles affecting overall layout, styles affect fonts, styles affecting the menu.
Within the blocks, the more general rules come first, and then more specific. That's how it goes in a nutshell, but, like I said, if you want to really get a good understanding, gogole around some css tutorials.
That's what I had to do when my hack attempts didn't work right back in the day!