Hey simran , You can apply either online or offline mode. Here I'm mentioning both the processes for applying in JNU :-

Online Application:

• Candidates can register themselves for JNU Admission to M.Sc, MA, MCA & MBA programme through online application process available at the official university website.
• Application fee of INR 300 (INR 2000 for MBA Gen. category and INR 1000 for SC/ST/ PwD) should also be submitted along with completed applications through the online payment modes such as net banking, credit/ debit card etc.

Offline Application:

• Candidates can also request for the application form to be sent by post along with the prospectus by sending Crossed Demand Draft of INR 300 (INR 2000 for MBA Gen. category and INR 1000 for SC/ST/ PwD ) along with the self-addressed envelope.
• DD should be drawn in favour of "Jawaharlal Nehru University", payable at New Delhi and the letter should clearly indicate the program of study for which the Application Form is required
• Natives of Nepal can also obtain the prospectus and application form by sending demand draft of amount Rs. 400/- or equivalent in USD
• Duly filled-in applications, in all respects, along with the copies of all the necessary enclosures should reach through registered post/ speed post at the following address:

Section Officer (Admissions)
Room No. 28, Administrative Block,
Jawaharlal Nehru University,
New Delhi-110067

Hope it helps.

All the best!!