Moved from the archived forum 2009-09-11 12:10:57
Themes are in Site building > Themes. There are four default themes. Switch to another theme by marking both the check mark box and the default button.
Add other themes by going to - http://drupal.org/project/themes or the - http://themegarden.org/.
Make sure that you choose themes that are available in your version of Drupal, that is v 6.x or 7.x.
To use a new theme, download it. If you are in the themegarden, click on the link to the drupal "project" page for that theme and download it from there.
If you have cpanel, the quickest way is to go to the cpanel file manager, navigate to sites/default/themes and upload the file that you downloaded earlier. Then choose extract.
For filezilla, you need to unzip/untar the downloaded file first (for Windows use for example Tugzip, for Ubuntu it is included in the OS), then upload the entire theme directory into sites/default/themes.
The theme will be immediately visible in the drupal themes section Site building > Themes.
Note: some, very few, themes are not perfect and may not show content properly. I recommend not to use them and delete them.
Just in case, when trying a new theme it is a good idea to keep the original theme's page active. Just open a duplicate of it in a new tab and switch themes there. If anything goes wrong, a new theme can break what you see but it is not likely to break your actual site. For example some check boxes to get back to the old theme might not be visible any more. But if you could get at them, they would work.
If that happens, you can still use the check boxes of the previous tab, save and switch back.