Since you have appeared your 12th boards this year, so you have to register under CA foundation examination 

Dear Saikat,

You have to write CA- CPT exam you have to do your registration in ICAI for Common Proficiency Course (CPC) of Chartered Accountancy to be eligible to write your exam. 

CA CPT exam will NOT be conducted after June 2019 session. CA CPT 2019 June session will be the last session of CPT exam. It has been decided in lieu of the introduction of new CA entry level exam, i.e. CA Foundation 2018, under revised scheme.After June 2019, CA Foundation will become the sole CA entry-level qualification examination. Until this period, both CA CPT and CA Foundation examinations will be conducted by ICAI.  

Good Luck!!