When you click on "I have downloaded the Information Bulletin" and click on "Proceed to Continue", it will take you to the application form. In the personal details column, Father's income is not a mandatory field. You can skip that column and still you will be able to proceed further with the application. The same way, you can also skip the Father's income column. Even that is not a mandatory field. You can enter your Mother's name and her Income and that will be fine. So do not worry about it. Please try it this way.