I'm graduated and want to become a govt. teacher or lecturer as I like teaching field. How can I do it after graduation?

You are following options to become a government teacher: (a) Undergo B.Ed after graduation degree to become a TGT teacher (b) Undergo post-graduation degree and B.Ed to become PGT teacher (c) Undergo PG, Ph.D and NET to become a lecturer in a university. Refer https://www.shiksha.com/careers/tea