Themes re-skin the layout by changing colours and images used in the design. Since a theme is just a CSS file and images, the layout of the page such as the location of the navigation is controled by the master page.

To create a new theme, copy an existing theme from the C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\THEMES directory into a new directory.

Edit the C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\1033\SPTHEMES.XML file and add a section for your new theme:

<Templates>
<TemplateID>NewDirectoryName</TemplateID>
<DisplayName>Theme Display Name</DisplayName>
<Description>Give Description of the theme</Description>
<Thumbnail>images/customimage.png</Thumbnail>
<Preview>images/pagepreview.gif</Preview>
</Templates>

Perform an IIS Reset and then select the new theme from the Site Settings page.

If you are making changes to an existing theme(e.g. your custom theme), you must also do a Ctrl F5 salute of course. If this doesn't work, you must then change to a different Theme and then back to your custom theme to see the changes.

Hi,

Sharepoint themes are not the so tuf as it is thought, its very simple to be made with your own design, to know more about it, look here to know how to make ur own theme,

http://santhoz-teaches.blogspot.com/2009/02/sharepoint-themes-unveiled.html

And to download lots of sharepoint themes, http://www.buytemplates.net

Regards,
Santhosh
http://santhoz-teaches.blogspot.com

Before you customize an existing SharePoint theme copy it and add a reference to it in spthemes.xml