Steps to implement an Exit

Hello,

I am relatively new into SAP and utmost of my experience is utilized in using standard SAP. Now couple of requirements are forcing me to go for customization and I need your valuable assistance for that.  I have got following two requirements,

1. Control creation of inspection lots based on production work centre & during good receipt against purchase order- Exit suggested is QAAT0001

2. UD check. If any of the inspection characteristic is rejected, then UD with 'Accept' valuation must be prevented- Exit suggested is QEVA0010.

I know I got to work with ABAP team to implement the solution but frankly speaking, I really don't know what to say to technical team except the exit names and my requirement.

Please share the steps/ method/ or any information which is required for applying an exit. I have never used an exit before.

I will be grateful to you experts.  This is really important for me.

Thanks,

Raj