Hi ,
Hope you are doing great.
You can join the Air Force by following ways:
If you have pcm in class 12 you can go for NDA exam which takes place two times a year after which if you cleared it, you will be called for ssb interview followed by medical. NDA has four years of training . The first three years has same for all wings but in the last year , according to interest and vacancies , you can join military , air force or navy and you will be sent for training.
AFTER GRADUATION:
You can go for CDS followed by same criteria ssb and medical and join the different branches.
AFCAT:
This entrance is selectively to join air force and you can join in its different branches like technical, ground duty , non-technical etc. According to the stream in which you have graduation.
Hope it helps.
Thank you