If you reach a certain position within your field you will be asked to become one.

Dear Udhaya Kumar

If you are well reputed in a particular field and your publications are good enough, then you will be called for review a manuscript.

Otherwise if your paper is cited in a paper submitted in a journal, the editor will ask you for reviewing. So all depends on how far you are shining in a particular research work

we have group of journal's editor where we can ask member to become reviewer

(before reading other responses) In my experience, after you have published your own credible work in conference proceedings or journals for a significant length of time, and thereby may have gained a fair degree of recognition and positive reputation in your field, invitations to be a reviewer may result. If so, then to the extent you provide good and timely reviews upon request, these opportunities will continue.

Thank you all

The editors will find you :-) then you may or may not accept to review.

Thank you sir

You must publish enough results in the area

If you are expert in some field.