Here is how to get it and use it :
If you are still on Joomla 3.2.x , then upgrade it to 3.2.x first using this link.
Once the upgrade is done, you should see this screen.
Click on "INSTALL FROM WEB" install and goto the next page.
You should see the new Joomla App Store.
Now you can simply search your keyword and download the extension.
It should look something like this.