Dear Priyanka,

As you are a girl so there is 2 ways so that you can join Indian Army after 12th and after 10th.

1. Army Soldier GD- For this entry you just need to complete your 10th with minimum 45% and your age should be under 17.5 to 21 years. For this entry you need to qualify for the written at first then they will call you for the physical and medical and after clearing every phase you will be eligible to join Army as a Soldier in Military police.
2. NDA Entry- In this entry you need 12th class certificate and through this entry you can join all three Army , Navy, and Airforce. Here you need to clear the written at first then they will call you for the 5 days long SSB Interview and if you have cleared the interview then you need to clear the medicals and secure a rank in merit list. After that they will call you for the training period of 4 years.

Good Luck :)