gistfile1.txt

// setup.hbs
{{#if stepOne}}
    <ol>
        <li class="active"><span class="step"><i class="icon-check"></i><span class="num">1</span></span></li>
        <li><a class="step" {{action "toStepTwo"}}><i class="icon-check"></i><span class="num">2</span></a></li>
        <li><span class="step"> <i class="icon-check"></i><span class="num">3</span></span></li>
    </ol>
{{/if}    
// {{#if stepTwo}}...

{{#if stepOne}}
    {{gh-setup-step-one nextStep=(action 'toStepTwo')}}
{{/if}}

// controller - setup.js

export default Ember.Controller.extend(ValidationEngine, {
    stepOne: true,
    stepTwo: false,
    stepThree: false,
    
    actions: {
        toStepOne: function() {
            this.setProperties({
                stepOne: true,
                stepTwo: false,
                stepThree: false
            });
        },

        toStepTwo: function() {
            this.setProperties({
                stepOne: false,
                stepTwo: true,
                stepThree: false
            });
        },

        toStepThree: function() {
            this.setProperties({
                stepOne: false,
                stepTwo: false,
                stepThree: true
            });
        },
    }
});

// component/template - gh-setup-step-one.hbs
<a class="btn btn-green btn-lg" {{action "nextStep"}}>Create your account <i class="icon-chevron"></i> </a>

// component/js gh-setup-step-one.js
import Ember from 'ember';
import {ValidationMixin, validate} from 'ember-cli-simple-validation/mixins/validate';

export default Ember.Component.extend(ValidationMixin, {
    actions: {
        nextStep: function () {
            this.attrs.nextStep();
        }
    }
});