Once logged in, go here.
Fill in the teacher's details under the heading 'Alternatively'
Ensure the dropdown box has been changed to 'teacher'
Click 'Register'
The staff member will receive an email (if you have used a valid email address), informing them know that you have registered them.
Contact the teacher to let them know what their password is.
Alternatively, they can click the 'forgot password' link and set their own (with valid email).