If you prefer video instructions, check out our How to Change the Default Drupal Theme Video Tutorial
How to change the default Drupal theme?
The default Drupal installation comes with several themes which can be changed from your administration area. Log in as an administrator,click on Administer -> Appearance and choose which theme you want to use for your website.
How to install new Drupal themes?
Drupal keeps its skins in the themes subfolder. To install additional themes, you can get the archived theme from theSiteGround Drupal themes gallery (these themes are compatible with Drupal 6.x) or from the Drupal official theme resource. Extract the files under the themessubfolder. This can be done through cPane l -> FileManager.
If you don't have cPanel or you prefer using an FTPclient, you can extract the archived theme to your comp uter and thenupload the theme's files to the themes folder in your Drupal installation directory.
You should now be able to see the theme at your Drupal Administration Area -> Appearance. Enable it and set it as default.
The Update t ab allows to view the outdated themes and get the new versions.
In the Settings section you can manage the global visualization settings for your web site. You can also overwrite them per each theme.