When you login your Claroline you can enroll on a new course via the Enroll on a new course link on the bottom of your page.
Select the desired course category and click on the pencil icon next to the desired course in order to enroll
Then you can click on Back to my personal course list to refer to your home page. You should be able to see the course you have enrolled on your home page now.
If you would like to start your Claroline LMS website in a few clicks, check the Claroline Hosting package. You may also check our great Claroline video tutorials with detailed step by step instructions how to install, configure and manage your Claroline LMS website just in a few clicks.