How to Secure Gmail Account.

• Login to your Gmail Account.
• Now open this link  https://www.google.com/accounts/SmsAuthConfig.
• Click on the Start Setup button.
• Choose a verification method.By selecting Text message (SMS) or voice call you will recieve the verification code on you phone either as text message or as a call. 

Enter the appropriate information about your country and Mobile Number.

• Choose SMS text message or Voice call option according to your need. (I prefer SMS text message).
• After giving your mobile number test your phone by clicking on the Send Code button.
• Now you will receive a verification code on your given mobile number and type that code in the verification field and click on Verify button.
• After verifying your number click on the Next button.

If you lost your mobile or your number is not available when you need it. For this you can save backup codes in to your computer.

• Click on Next button again.
• Here you will see 10 Backup verification codes. Choose Print codes or Save to text file option whatever you like but keep it safe and don’t lose it.
• Check mark the box and click on Next button.
• Here give your working alternative number. And click on Next button.
• Now again click on the Next button again and then click on the Turn on 2-step verification button.