Remove/edit info in header

I would like to edit the footer in my Attitude child theme for my site, but I can’t seem to make it happen, even if I follow the directions outlined “>here. As I mentioned in that thread, if I create a functions.php file and copy-and-paste the code that’s listed in that thread, the only thing that ends up happening is that I can add a line that has the year for copyright, and my site’s link. I can’t actually delete anything that’s there – the stuff that is added ends up above the copyright/site link/citation that was there before. I hate to beat a dead horse, but… does anyone have any other suggestions for getting this to work? It also appears that there is a line break on my page between “Powered” and “by: WordPress.” How can I fix this in my child theme? Can someone give me explicit directions on where I should place my functions.php file? I have been putting it in my Attitude child theme folder, and the only other file here is my style.css. Is that the wrong place to put it?

Thanks!