How to write a linqdatasource _inserting (object sender,linqDatasourceInsertEvent args)?

Question

How to write a linqdatasource _inserting (object sender,linqDatasourceInsertEvent args)?

I use a detail view (select from masterview already), but when i write back to sql i will take either a session[userid] or master gridview1.[userId] selected value.

Or just simply ask for Inserting function for Linqdatasoure with LinquDataSourceInsertEvent?