Calendar application

[eluser]bondjp[/eluser]
Hi guys.
I need to build an aplication where users can select a day in a calendar and then select an available hour to book a doctor appointment.
The application will allow the doctors to book appointments they have on the site also.
I will need that this app to manage several users trying to book an appointment at the same time (ajax?) and that it could update the appointments on doctor's side if he has the calendar page open.

Now, i'm new to CI. I used to programm but that was a long time ago(17 years) so i'm returning to this life and re-learning how to do it.

I would like to know what's the best route to take in order to get this thing done.
What do you guys think it's better so i could do this.
Thanks.