SQL & PL/SQL

Hi,

how do I use a cursor inside a stored proc?..does anyone know a good site which helps me to learn

I am doing a login application where users are created and autehnticated

I am trying to write a stored procedure which will actualy get input from the page and it has to check for the
accountno (input) in a employer table , if it exists then it has to perform insert or else it should send some number which will let me know in the front end that this user is not valid and should not be allowed to register..

can anyone help me start..i am new to oracele

thanks
Jessica