STS#0 means the STS folder under ..\12\TEMPLATE\SiteTemplates and the 0
means Configuration 0 (zero) in
..\12\TEMPLATE\SiteTemplates\STS\XML\ONET.xml

So, if your custom  Site Definition is in a folder called XYZ under
..\12\TEMPLATE\SiteTemplates and you want to use Configuration 2 in
..\12\TEMPLATE\SiteTemplates\XYZ\XML\ONET.xml you would use:

Where did it save custom  template which is "save as template" in site
setting?

Sorry, I missed the fact that you saved the site  as an SharePoint
Template Package (STP).

STS#0 is based on the site  Definition being in the STS directory. Team
site is Configuration ID 0 and blank  Site is Configuration ID 1. But
since you saved your site as a template  it won't be in the Site
Templates directory of the 12 hive. That's only for Site Definitions.
It will be in the Site Template Gallery of the top level web site of the
Site collection where you saved it. You will need to get the Template
ID programattically. You can call the GetCustomWebTemplates method of
an SPsite object to get a collection of site templates available. Step
through that collection until you find  the site template with the Name
you gave yours. Get the ID of that SPWebTemplate object. That is the
template ID you want.

I had a little time, so I put the necessary code into an STSADM
extension. It can be downloaded (for now) from my blog:
www.schaeflein.net/.../BarracudaAEDUpdated.aspx

Please let me know how it works. Thanks.

I can't download your file..
anyway
I did it with a different way.

stsadm -o addtemplate -filename \sitetemplate.stp - title sitetempalte
stsadm -o enumtemplates

then I can find  the ID like _GLOBAL_#1

You clicked on the .stp file in the gallery list and saved it locally,
right? I would like to understand so my extension documentation can list
all alternatives.