Well, for those who haven't got their nbi clearance yet, I made a simple instruction for you dear readers. Check it out.
You will need to sign up first NBI site
Fill in the boxes with your personal information then click on apply for clearance. It'll prompt you to the next step.
Choose which branch you're planning to apply for the clearance.
Choose the date, is it AM or PM, the purpose, and lastly the mode of payment.
I paid for 140 php through LBC after I got the my reference number and a confirmation was sent to my email account immediately after.