Additon of new fields in Ad hoc query

Hi

I Have to add two new fields to a infoset.

i am very new to infoset, please guide me on this.

1) how tto add the field.

2) How to write the logic for the added fields

a) using select and function module.

the infoset is related to Hr module.

i have to use infotype 0008 and 1005 (HRP)

hope to get the help on this soon.

Thanks in advance .

Anuj