Hello radha,
To get a seat in government medical college :

1.fill the neet ug /pg (whichever you want to get into) form
2. Attend the neet exam
* wait for the results, compare cut offs.
3. Fill forms for medical counselling.
4.Attend the medical counsellings

And you will get the government medical college you are eligible for.

Hi
In order to secure a seat in government college you need to score 620+ marks to increase your chances .By scoring these marks you have fair chances of getting college of your choice . You can apply for government colleges under 15% all India quota and 85% state quota . Cutoff of every college is different and varies every year depending on number of students appearing in exam, difficulty level of exam, students scoring more than you and your category.
Hope this helps