the code In the defalt.php of stopdesign theme :
Description
You can insert your Gallery description using on the Admin Options tab.

but I do not find the Gallery description on the admin options tab,where is it?

How about the theme options tab?...:-)

there is no Gallery description on theme options tab.
I found all options ....

Well, in my install there is (options > theme options, at the bottom)

thanks ,different theme has different theme option.

And of the distributed themes, only stopdesign uses the gallery description option. If another theme wants that option it should include it in the themeoptions.php script.