WordPress does allow you to download and use custom themes for your blog. If you would like to use a different WordPress theme for your blog web site, first of all you will have to download it to your local machine. You can search for a WordPress themes gallery online and download free themes.
To install a WordPress theme, log in to the WordPress Dashboard panel by using the admin username and password. The URL for the WordPress Dashboard panel is usually http://YOURDOMAIN.com/wp-admin. When you’re logged in, you should see an option “Appearance” on the left side control panel of the Dashboard.