Auto Generate Email

Auto Generate Email

Hi I am a very new user having been forced to transfer from Dabble.
 
We have an instruction booking system for appointments which are completed online. once we receive them we validate then confirm appointment time.
 
To explain fields that appear on the web form are something like this
 
Instruction Date (Auto completed at time of input)
Client Name (Input by Client)
Detail (input by client)
Appointment (Completed by us on validation)
 
Within the form we have additional fields that we comlete on validation and we then confirm the appointment. What i would like to do is automate that process so that when we complete the appointment field an e mail is automatically sent to the client and vendor confirming the appointment. 
 
It looks like I can do this with the script but have no idea where to start