I found some examples of custom function. By checking code of some websites I created my custom function, but I'm unable to use it. How to call & use following functions?

goHome: function goHome(e) {
    //TimelineMax code
    //TweenMax code
}

 openWork: function openWork(e) {
     //TimelineMax code
     //TweenMax code
 }

  openAbout: function openAbout(e) {
      //TimelineMax code
      //TweenMax code
  }
  goToProjects: function goToProjects() {
    //TimelineMax code
    //TweenMax code
  }

Sorry, I'm not quite getting what it is you're trying to do. Are you trying to create a jQuery plugin?

Per jQuery's official documentation:

$.fn.greenify = function() {
    this.css( "color", "green" );
};

$( "a" ).greenify(); // Makes all the links green.

More information at https://learn.jquery.com/plugins/basic-plugin-creation/