How to make a QR code
Goto http://qrcode.kaywa.com
Select the content type as you wish . if you want to add a Url on QR code select url and add your URL
and Press on the size if you want to make Size Small , medium or Large then Press the Generate Button. Download the QR code image on Computer.

Decrypt a QR Code:
Goto http://zxing.org/w/decode.jspx
Click Browse and Uplod the picture to the website and you can decrypt it and there are many other methods to decrypt QR code .The Device which to Decrypt QR code are QR barcode readers and camera phones with QR CODE Reader Application on it .