Hi Warren,
The attached picture is of the left side navbar in Moodle 2.4, but the design has been essentially the same since Moodle 2.0. This is the main course page. In other words, the page you get when you go into a course, not when you first login to Moodle.
At this point, I've gone into the current course (Ben Test), clicked on participants, clicked on the name of a participant, clicked on activity reports.
I'm beginning to suspect that your role is administrator and that you are looking at the front page of the site where the left side navbar is labeled "Site Administration." There you WILL find a list of Users.
EDIT: OH! You are in the Course Administration navbar. That's where "Users"& "Enrolled users" are. Probably, with the Navigation bar collapsed. Look at the second picture in this post. You will find a little tab in the upper left corner of your screen that says "Navigation" sideways. Click on it. Then click on the triangle pointing to the right. This will expand the Nav bar. And then you are in business!