I am hindu boy I need to change my caste to penta coast. Where I can get help for this?

Do you mean Pentecostal? If so, that's not a caste. It's a church body and doesn't change your caste.

It is a religious group, you become one by accepting their religious beliefs, being baptised into the religious faith that they teach, and being a church member.

It is not considered a CASTE it is merely a religious denomination.

I'm afraid we need more information about exactly what you want before we can be of assistance.