To submit your podcast to iTunes (or any other podcast service) you need to first get your podcast feed URL. This is available from the Publishing tab in the Podcast > Settings page. The URL labelled Complete feed is the URL for your full podcast RSS feed.
Once you have this URL you can submit it to any podcasting service that you like. To do this for iTunes, simply go to their submission page and click on the ‘submit your RSS podcast feed URL’ link in step 5. The first 4 steps are all taken care of by Seriously Simple Podcasting so all you need to do is submit the feed URL.
When you submit your podcast RSS feed to iTunes, all of your podcast information (title, image, etc.) will be automatically fetched and displayed within the iTunes library.