Step 1 : First open government official UIDAI Aadhaar card website or click below.
Step 2 : Now you can see a form, that you have to fill step by step, if you are downloading aadhaar card by using your aadhaar card number so first you select Aadhaar option.
Step 3 : Enter your Aadhaar Number, Full Name & Pin Code and then enter text displayed above image.
Step 4 : Next click on Get One Time Password button, wait for few seconds SMS of OTP on your aadhaar registered mobile number, if not received OTP then Click Resend One Time Password Button,
Step 5 : Now enter OTP in Enter OTP box and click on Validate & Download button.
Step 6 : Finally your e- Adhaar start downloading of PDF file and you only can open that e- Aadhar because PDF that file will have a password protected.
Step 7 : Please use your postal code as password to open the E-Aadhaar pdf file.