You can have users get automatically assigned to a set of courses that you have put together in a group. To do so you need to create a new group, set a property for that group to be a default group and then assign the courses you want to it.
Let's review the process step by step in details. To start with, log in your system as administrator and from your Administration dashboard, visit the Groups section. Over there click to edit (1) or add a new group (2).
If you decide to add a new group, once you have set up a name for it, click on the Advanced settings link (3), to access more setting options about the group.
Check in the Default system group option (4) to make this group a default system group. Once you have done so, click to add the new group and then move to the courses tab of that group.
Select the courses you want to assign to that group. Once you have done this, you are ready to go. Newly registered users to your system will automatically get assigned to that group and in addition will automatically get assigned to the courses that belong to that group.
You may define more than one Default system groups, which means that all courses that belong to those groups will get assigned to newly registered users.
Each group that is set as default with have the corresponding label next to its name (5) in the tabular list of groups.