Hi
Once you get your degree completed i.e become an MBBS graduate, you need to apply for the various vacancies that are released for various government hospitals.
You can find information about these vacancies in the newspapers under the employment sections and newspapers dedicated specifically for employment purposes.
As soon as the posts are vacant, vacancies are released by the concerned authorities. They then have certain tests or interviews conducted to select the candidates suitable for the post. As you gain experience, you'll stand much ahead of the potential candidates. You can choose to apply under any post you find that suits you and pays you appropriately.

Hope this helps
All the best :)

After earning your MBBS, you must apply for the positions as soon as the local announcement is released in order to be considered for the government hospital. In the employment newspaper, all job announcements for the government are displayed. So, by reading the paper, you may learn about the various positions, and if you meet the requirements, you can apply for the positions.

Seniority and your specialization will also hold very much importance for your application in the government hospital and moreover the government pays handsomely to doctors. Hope I have answered your question. All the best!