how to upload material master using BAPI

I have a flat file with 3 fields MATNR,MAKTX,MEINS and I want to create material master with 2 views basic data1 & basic data2 with three fields using BAPI

Can anyone tell me how to do this only using three fields and 2 views

and also i want to know what is the exact difference between session call transaction BAPI and LSWM methods.

Thank you,

Pradeep Reddy M.