If you would like to add credits to a member so thay they can purchase activities using these credits you can manually assign a user credits. You must also make sure you have given the activies you want to be puchased by credits a "Required Credits" value (in Admin>Data Settings>Activity>Select an activity) so the system knows how many credits the activty is worth.
To Assign credits to a Member, go to Admin>Data Settings>Credits (talk to your account manager if Credits is not available in the dropdown), and click "Create'Credit'". In the new pane on the right, assign the activies the credit is valid for and also the value of the credit. Finally give it an expiry date and the member you wish to assign it to from the dropdown and click add.
The member you select now has credits assigned to them, to use these credits the member must log into their account and click the "bookings" link.
NOTE: You can also set up the system to assign credits to users when a schedule is cancelled using the cancel day functionality in Admin>Data Settings>Schedule, please contact your account manager to switch this functionality on.