How to do OOPs in ABAP.

requesting you all,

Every reply will be awarded, if answered for atleast a question in useful manner.

1) Apart from Normal abap progrmming where we use abap-oops? say some applicatons please as detail as possible.

2) How to difine and implement classes? 
a. if i want to dispaly get records from a database table and display.
b. if want to do calculations on the retrived data.

3) I am not sure about this, some where i have seen implementing objects as internal table which stores couple of records. How to do this?.

4) give some sample codes with little bit descriptions please.

Regards

Praveen