Develop a mebers zone with a calendar

We as administrators, whenever we have a new customer, we add on the calendar the hours this new member will assist to the class (can be 1 hour or 2 hours per week). And every time when a customer wants to unsubscribe, we will remove from the calendar the hours that this member used to assist to. Maximum number of members per class is currently 6 (this number should be configurable) When a class is not full (for example, with less than 6 students) will be shown in green. When a class is full (for example with 6 students) will be shown in red. Each student will have a username and password to log in. Each student can release up to a maximum of 2 classes a month, when for personal reasons can not attend that class. The student who has released a class, that class can be recovered (to a maximum of 2 classes per month) in any free time, within a month that has liberated the class. We as administrators, we label each class with a level (low, medium, high). This would be in text format, not colour format. This functionality should allow new customers create a new user (login and pwd) , to perform operations on the tool.