Steps to load data from R/3 to BW

Hi all,

1. I am loading data fromDS : 2LIS_12_VCITM to cube. Can somebody explain what steps we need to follow in R/3 and then in BW.

2. Also i have a Z - Extract Structure for 2lis_13_vditm,which has additional fields, how or where should i link 2lis_13_vditm with Z-extract. And how does the newly added fields get value?\

Thanks,

Gowri