Anshu,
The application forms for Delhi University Joint Admission Test have not yet been released by the University and that's why you are unable to find it on the website . DU JAT 2019 Application Form will be available online at www.du.ac.in. Wait for it.
This is official website of DU and official notifications will first be released here only, so be in touch with it to be updated.
Wish you luck !:)