After you log into Moodle, on home page you can see the list of the active courses of the current semester. At the bottom of the list, there are other categories, such as the placement exams or extracurricular courses.
All courses are in alphabetical order by course code. Pay attention to the section number of a course that might have multiple sections, and to the name of the instructor.
To search your course, use the Search courses box. Type in the course code or name of your course and hit Go.
When you select your course, you may be asked to type an enrolment key (password) that it is usually given by the professor either in the syllabus or during the first class period.
Type in the enrolment key (use the Unmask feature to make sure you are typing it correctly) and select Enrol me. You only have to enter the enrolment key once. After the enrolment you will not be asked to do it again and you will be able to access the course materials.
Once you login to Moodle, your course(s) should appear on the right side of the page in the My courses box.
On the right side menu, under My courses, you will only see the active courses of the semester. You can also find your courses in your Dashboard where your full list of courses will be displayed under the heading "Course Overview". The Dashboard can be accessed on the left side menu or from the user menu top right of the screen once logged in.