ember application.hbs page not render other page

Ember CLI version 2.7.0

In templates folder I created two files, application.hbs and post.hbs
application.hbs

<h2 id="title">balabala</h2>

post.hbs

<h3>I am from post.hbs</h3>

I expect "balabala I am from post.hbs" shows in browser, however I can only see "balabala".
Anybody could help? Thanks.