We're at the final step! Uploading your app is where all the real fun starts, because now you get to see if it's all working.
Next, you'll need to log in to your Zendesk account (you will need a Zendesk account in order to upload any apps, sign up here).
If you run into any problems, be sure your .zip does not have any odd files or directories - which includes anything that might be hidden. If problems still persist, we're happy to help on the Apps Forums.