Adding Gradle to PATH
The path /myusername/Applications/gradle-2.6/bin probably doesn't exist except your personal user folder is in the root of your main volume - which would be very, very uncommon on a *nix system.  

Depending on where you've installed Gradle the proper path might be:

/Users/myUsername/Applications/gradle-2.6/bin or
/Applications/gradle-2.6/bin


So change the export line to

export PATH=/Users/myUsername/Applications/gradle-2.6/bin:$PATH or  
export PATH=/Applications/gradle-2.6/bin:$PATH