Hi Indira,
you can import a flat file into hana using below steps-
Login to SAP HANA Development - SAP HANA Studio
File
->Import
->SAP Hana Content
->Data from local file
Here you have 2 options-
1- to insert into a new table
2. you can create a table using sql command in your schema using hana sql editor and try giving the same table name for importing flat file.
(here you have an option of creating your sql table with default values acceptable that you are looking out for.)
Regards,
Saritha K