To practice and get converted to Hinduism, there is no official conversion process or religious ceremony. One needs to have the will and the commitment only to study the scriptures and abide by the rules and practices followed in the Religion. In India, you can visit a nearby Arya Samaj temple and show your willingness towards conversion to Hinduism, post which they will issue you a certificate of conversion. The conversion certificate needs to accompany the application form for notification in the official Government Gazette. This means changing religion (due to self-belief, marriage, or divorce) is legal in India provided the same is in good faith and not because of any coercion or application of force.
The Procedure to change your religion leaglly is as follows :
1) A religion affidavit is to be prepared on stamp paper with details like name, old religion, new religion, address, which is notarized by a notary public.
2)An advertisement of the person is placed in a widely circulated newspaper to ensure that there is no public objection or illegal reasons behind changing the name.
3) The national gazette which is an online record published by the central government of India is to be notified of the religion change to alter government ID.
4)The religion change declaration is then published in the e-gazette which will take 60 days to appear.
Reference: Article 15 Of the Constitution of India.