At first keep following identities
1.Gas connection number
2.E-mail ID or Mobile number
Then do like this, Register your aadhaar number from this link
>> https://rasf.uidai.gov.in/seeding/User/ResidentSelfSeedingpds.aspx
After register aadhar number they will send you a conformation code in to your mobile or your mail id, Then fill that conformation code on conformation page. now complete your registration.
Then you can download a form for application to bank following link
>> http://www.hindustanpetroleum.com/Upload/En/UPdf/AAdhaarHP1.pdf