HI, 

In order to apply for nata , you need to apply from their official website. The online portal to apply for the exam will start in around third week of January 2019. Until then you cant access the portal link. Once the application portal is open which is in third week of january, go to their official website- www.nata.in/ and they will guide you to fill and apply for the exam. For more information on nata exam, careers360 has put up articles for all upcoming entrance exams, you can check here - https://engineering.careers360.com/articles/nata 

hope it is helpful. 

Good Luck. :)