How to make a child theme

Hi.
Thanks for the great theme.
I tried to create a child theme of Manduca, but it seems that I’m doing something wrong and I can’t make a working child theme. I followed the www.ads-software.com guide but none of the suggested methods works.

Can you please provide the code I need to put either into the functions.php file or the style.css file of the child theme.

Thanks in advance
Lena