Kindly help about the esi

Kindly Help me about the following information :-

i) How to register for the ESI ? What are the papers required at the time of registration ?

ii) Is the return of ESI is compulsory to file ? If yes when and how ?

iii) What is the date of the payment of ESI and whom to pay and what is the way of paying ? Is there any challan ?

Please Help me regarding the above ........................

*******************Thanks in advance***********************