firstly open settings in amazon fire phone and select option
"Applications and Parental Controls" like this
now select option " Allow Non Amazon app installation " like this
now turn on "App Installation " option on top of options like this
now click OK to allow your amazon phone to install non amazon apps.
now go back to your home menu of your phone and open silk browser like this
now open whatsapp from menu tab like this
now scroll down and open a link to download APK file of whatsapp.
after clicking a new tab will open
now scroll down to click on blue button to download whatsapp APK file like this
now you can see your downloading file like this
now open your storage of mobile phone and check your downloaded whatsapp file like this
now open your downloaded file to install like this
when you click to open the file, it will ask you to download it. click on next option like this
you can see your installation under progress like this
when whatsapp application install, click on option " open " like this
now whatsapp application is install.
open your whatsapp application and it will ask you to click on the option " agree and continue" like this
now choose your country and enter your mobile number like this and whatsapp will be install....