IIM

Please take one step at a time.
1. Complete your graduation.
2. Pursue your post graduation and try to score more than 55% marks.
3. Try and pursue Masters program in the relevant area from an institute where you would like to pursue PhD. In such a case, admission for PhD becomes easier.
4. One needs to clear UGC exam NET followed by an Interview of other as specified by the institute for pursuing PhD.
5. Once you qualify in NET, you also get grant (monthly stipend) for pursuing your PhD.
6. Incase, you are not keen on grant, you need to to clear the open test as specified by the respective institute.
7. After getting admitted to a PhD program, one needs to complete some course work (which may even include conducting lectures for under graduate/graduate students) for acquiring requisite credits. Followed by submitting a proposal of research (synopsis) prepared in consultation with your guide (you will have the option to decide your guide from the existing pool of professors in the said institute) and seek its approval approved by doctoral committee.
8. Once, its approved, you can write your thesis & submit it for granting of PhD.
9. The entire process for PhD may take 3 to 5 years depending on your effort, topic & support from your guide.
10. Fees would depend on the institute & topic for research.
All the best for your PhD.