Mapping a Model in WebDynPro

Hi,

I'm Developing a Project in Webdynpro(java) to communicate R/3 backend.I have used Bapi_Material_SaveData .

1)how to map BAPI internal table values to context .... ?

and,

2)In Bapi_Material_SaveData thr is a node/class called materialDescription .under this thr is a field called "lan" .In my coding i want to set this as "en" as a default value...Hw to do this ?

Help me out.