Depending on the vacancy created you have to apply for the exam. Now you didn't provided your state name. You have to visit your respective State PSC website and if any vacancy notification is there you can apply for it.

**As you haven't provided proper details I can't provide you specific answer.

You can visit your state PSC Website by typing on google Search : <Statename>PSC. For example if you want to live in Kerala then write on google search Kerala PSC.

I hope this answer helps. All the very best for your future endeavors!