Finding your course site
The front page of the moodle site (after successful login) contains a list of categories in which the courses within the moodle site are organised. On either side of the course listing are a number of side blocks (discussed in more detail later in Moodle side blocks).
To find any course site you may be able to locate it simply by browsing the categories and course listing directly. However, the fastest way to find a specific course is to use the Search courses tool located at the bottom of the course listing page (see screen shot below). This generally does an excellent job at returning sensible results, especially if you use a very specific term such as a course code e.g. COMP10900. (Note that not all Computer Science course unites are using moodle, but if you are sure a course unit should be there and still can't find it, then seek help from your course unit tutor.)
Another way to find a course you are enrolled on is to may use of moodle's my moodle feature. My Moodle is a customisable "dashboard" page for providing users with links to their courses and activities within them, such as unread forum posts and upcoming assignments. Therefore if you are enrolled on a course, it will be listed here.