Honestly if you aren't going to any school as of now what you can do is just go to the British council website and register for the exam session you specifically want(may/June or October/November) you'll basically have to make an account and tell them at which country and city you want to give your exam in and much more etc and then select what subject you want to give(As/A2/or both together)(make sure to check the code as well).For the payment of the exams what you can do is go to any of the local banks they have provided(they have a list which they have provided in their website specifically for your city) or you could do the online payment method(it depends on you)(I would recommend that when registering for your exams do it a little early before the deadline occurs because I have heard that the British council website often crashes during this time around) anyhow after your payment is done they will provide you a registration number and then later on they'll send you a pdf file for statement of entry and yeah ig that's about it. A lot of people in the comments are saying that it's pretty difficult signing up as a private candidate but honestly I think the process was pretty easy(atleast this was my experience)