amitkumarRoy

({
    handleClick: function(cmp, event, helper) {
     var navService = cmp.find("navService");
     var pageReference = {
                         "type": "standard__component",
                         "attributes": {
                                         "componentName": "c__WebinarOverride"
                                       }, 
                         "state": {
                             'message':'This is the target page'

amitkumarRoy

<aura:component implements="force:appHostable,flexipage:availableForAllPageTypes">
 <lightning:navigation aura:id="navService"/>
 <lightning:button label="Navigate" onclick="{!c.handleClick}"/>
</aura:component>

amitkumarRoy

<aura:component>
    <lightning:inputRichText value="HELLO">
       <lightning:insertImageButton/>
    </lightning:inputRichText>
</aura:component>