Dynamically Creating Lightning Components

Sample Component:

<!--
Name: Sample.cmp
--> 
<aura:component >    
    <div class="slds-m-around_xx-large">
        <label class="mdp-form-user-element__label" id="enteredName"></label><br/><br/>
        <lightning:button label="Add Your Name" variant="brand" onclick="{!c.handlePopup}"/>
    </div>
    {!v.body }
</aura:component>

Sample Component JS Controller:

({
    handlePopup : function(component, event,helper) {
        //Create Dynamic Component
        $A.createComponent('c:SampleModalPopup', {
            title: 'Please enter your name',
            
        }, function attachModal(modalCmp, status) {
            if (component.isValid() && status === 'SUCCESS') {
                var body = component.get("v.body");
                body.push(modalCmp);
                component.set("v.body", body);    
            }
        });
    }
})

ModalPopup Component:

<!--
    Name: ModalPopup.cmp
--> 
<aura:component >
    <aura:handler name="init" value="{!this}" action="{!c.doInit}"/>
    <aura:attribute name="title" type="String" />
    <div aura:id="modalDiv">
        <div role="dialog" class="slds-modal slds-fade-in-open">
            <div class="slds-modal__container">
                <div class="slds-modal__header">
                    <button class="slds-button slds-modal__close slds-button--icon-inverse" title="Close" onclick="{!c.handleCloseModal}">
                        X<span class="slds-assistive-text">Close</span>
                    </button>
                    <h1 class="slds-text-heading--medium">{!v.title}</h1>
                </div>
                
                <!--Modal Box Header-->
                <div class="slds-modal__content slds-p-around--medium">
                    <input type="text" placeholder="Please enter your name" id="userName" autofocus="autofocus" class="slds-input"/>
                </div>
                <!--Modal Box Button-->
                <div class="slds-modal__footer">
                    <lightning:button label="Submit" class="slds-button_brand" onclick="{!c.handleSubmit}"  />
                    <lightning:button label="Cancel" class="slds-button" onclick="{!c.handleCloseModal }"  />
                </div>
            </div>
        </div>
        <div class="slds-backdrop slds-backdrop--open"></div>            
    </div>
</aura:component>

ModalPopup JS Controller:

({
    doInit : function(component, event, helper) {
        console.log('Modal Popup Load');
    },
    
    handleSubmit : function(component, event, helper){
        var userName = document.getElementById("userName");
        var enteredName = document.getElementById("enteredName");
        enteredName.innerHTML = userName.value;
        
        var popupWindow = component.find('modalDiv').getElement();
        if(popupWindow){
            popupWindow.style.display = 'none';
        }
    },
    handleCloseModal : function(component, event, helper){
        var popupWindow = component.find('modalDiv').getElement();
        if(popupWindow){
            popupWindow.style.display = 'none';
        }
    }
})

Output: