For required courses within credentials, you can set up your credential topics so users can take these courses at their leisure. When they open the credential, they will have the option to launch any of the courses directly from that page.
You may find this more effective than the alternatives, which would be assigning out all of the training via Create New Assignments (more work for the administrators) or making all courses available for self assign via the Course Library (any user could take them, even those not in the specific credential).
1. Under Administration click Manage Credentials, and then click on the credential you would like to edit.
2. Click the gear icon next to the credential topic.
3. A pop up window will appear. Fill the circle for Option 1 under User Options, 'Courses/Custom Activities are viewable and can be accessed from the user’s detail page'. Then, click Save.
4. If there are multiple topics in the credential, repeat steps 2 & 3 for each topic.