From PowerPro's 'Home' menu we're going to select 'Trainers Assessors' this will open the Trainers and Assessors window 



From here we're going to select our Trainer, go to the 'Vocational Competencies' menu and click 'Add V.C.' this will open the 'Trainer: Add Vocational Competencies' window

You can search for the unit/s required or manually scroll to locate it, once you've got your unit/s make sure you tick the box in the add column (you can do multiples!) once done click 'OK' and you're all set!