how to get my cast certificate in karnataka

respected sir .m sumith lama .from Bangalore .my father name is Sunil bahadur lama .my grand father name is Suraj bahadur lama .we r having trouble to .make our cast certificate in Karnataka .we belong to lama (tamang cast) but we r not able to make our cast certificate .we r having trouble for our studies .we can't able to get higher education hear because we don't have our cast certificate .how can I make my cast certificate . please tell us sir . from childhood we r in Karnataka only .but we need our cast certificate .my grand father lefted Nepal about a 60 year ago .so we r having trouble to get higher education