Method Number One
- Launch your internet 'Browser' app - it is a icon of a dark blueish globe
- In the address bar, delete every thing that may be there and then type: www.whatsapp.com and then click Go or the Enter arrow
- Locate and click on the green button that reads "Download now" and confirm if necessary.
The Whatsapp messenger app should download and auto install on to your device but if it does not install, then you have to install it manually.