Need help with a child theme on wordpress.org

Hi, I am new to wordpress.org and I understand that I should set up a child theme over my twenty twelve theme. So if I need to update and tweek my site, I won't lose all the data. Is there anyone who can walk me through the process, so afraid I will mess it up. Thanks.

Thank you, Brian and Steve,

I will have a look to see if I can find a theme that works for me.Don't really want to learn CSS or PHP .

Once again Thanks.

It really depends on exactly what it is you want to modify. Changing colours/background images are easily done by editing the php files in a text editor like Notepad++.

Dear Brian

Thank you, but I already have the twenty twelve theme ( parent theme ) I just want to modifer it or add to the functionality of this theme. From what I have read the easiest way to modify an existing theme is to create a child theme. I just don't have enough knowledge on wordpress at the moment to start messing with the directory files or is it easy and I should just go for it?