How to develop child theme for thesis

I'm sure Thesis/DIY Themes offers tutorials for that. Have you bought or just downloaded the theme "somewhere"?

Shalu, I have not created any child themes, but as somatic said, the best and easiest way with Thesis is to make your edits to the custom.css and custom_functions.php files. These files become portable and can be used in any Thesis design.

If you really want to create a Thesis child theme, here's an article from Kristarella that I bookmarked which guides you through the the steps. http://www.kristarella.com/2010/10/wordpress-child-themes-and-thesis/

Hope this helps.

The Thesis framework uses a unique system to customize while inheriting the parent theme's functions and styles, different from the typical Wordpress method of child/parent themes. You don't actually build a separate theme folder with Thesis - you edit the files within /wp-content/themes/thesis/custom/ (or if it doesn't exist yet, change the name of the "custom-sample" folder to "custom" and then edit the contents).

There are two basic files to start with - custom_functions.php and custom.css. Place any code you would normally place in the functions.php file of a child theme into custom_functions.php, and place any CSS you would normally place in the style.css of a child theme into custom.css.

Thesis reads these two files and automatically injects them like a child theme when rendering. There's an images folder inside of /custom you can use for your graphics, too.

The great thing about this system of customizing Thesis is that it's completely self-contained - you can copy your /custom folder to any other site running thesis, and your customizations also won't be overwritten by updates to the Thesis theme itself.