Custom Training tags are for all levels of PEAK subscriptions that allow you to create training sessions that individual to you.
Go to Settings in top right corner
Go to Custom Training Tags
Click on "Add Tag"
Type in the session type individual to you
Click "Add Tag" when complete and it will be listed among your session types when you next go to log your training data
Custom Training tags though do not have a session load modifier so miss out on the logic benefits that these bring