Program logic for new custom infotype

Hello Experts,

I have a requirment like this, i need to create a new custom infotype with a single field value.

and after creating when ever i goto pa30 and see this IT.

and if i click on Over view button, the data from the new info type need to be displayed with some additional data from

IT 0002.

So where we can write this logic , when we click on over view button.

Please let me know where i can read the IT0002 and i can display with new IT.

Thanks,

Suresh