2-step Verification for both Gmail and Facebook

To use 2-step Verification you have to install any Bar code scanner to enable it.
http://goo.gl/kOkW7P

Gmail:
Step 1: Login to your Gmail A/C.
Step 2: Click on Account under your mail id. (You can find it at top right corner image section)
Step 3: Go to Security Tab then click on Settings option in 2-step verification.
Step 4: Select Google Authenticator App. Download App from play store. http://goo.gl/yI81Is
Step 5: Open the app in your mobile and scan the barcode using the bar code scanner.
Step 6: Enter the code provided in the app. Synchronize will be done automatically.

Facebook: 
Step 1: Login to your Fb A/C.
Step 2: Go to Settings. Click on Security(You can find it at left panel)
Step 3: Click on Code Generator then click on Set up and again type your Fb password. 
Step 4: Open the bar code scanner and scan the app and enter the code. 
Step 5: Click on Confirm. 

From the next time on-wards when you will open the a/c enter the code using the Google Authenticator App.