I came across this document explaining 'Authorizations in SAP' and how to create and implement them in brief and simple language : Authorization Objects– A Simple Guide . At least it can get you started on the concept of authorizations in SAP and naturally, you can explore later. This document demonstrates :

• the creation of Authorization field using transaction  SU20,
• the creation of Authorization(Object) Class, Authorization Object using transaction SU21,
• the creation of Role using transaction PFCG and generation of Profile,
• checking the user-authorization inside the ABAP program by using AUTHORITY-CHECK statement and checking sy-subrc value thrown by it.