how to fetch data after adding new tab & custom field to migo

dear experts,

i have created one new tab to migo .. & two custom filed ...

1 ) net price (netpr)

2) net value(netwr) ( both field are from ekpo table )

i have requirement that when we enter purchase order... it will show line items ralated to that purchase order..

when we click on that line item : both field should show the value..

i have used badi : mb_migo_badi.

i am not able to get where i will declare my code ( like internal table & work areas ) so, that i can fetch these value..