"Learn the Process for Developing Lightning Components"

I've created "myFirstComponent" with the following on their .cmp file:

<aura:component >
	 I am proficient in JavaScript
</aura:component>

After that I've created the "harnessApp" Lightning Application with this on it:

<aura:application >
	<c:myFirstComponent />
</aura:application>

And the error is ...