You will have to open a trading account first with Kotak Securities, to register for Trade API. To sign up - click here.
Once your account is open, you can register for Trade API by clicking here. You will be emailed your API webportal credentials.
To Know more view the below video:
A Step-by- Step Guide on How to Register For Trade API | Kotak Securities
For more videos on Trade APIs at Kotak Securities check this link: