On the top of your menu bar should be the cloud app. If not then go to Applications and double click Cloud, then it should show up on the menu at the top. Click once on the cloud icon (in your menu) and open "Open Web App".
Then you can see the contents and manage your uploads from there.
Here is a screenshot:
Ok, I have OS X Mountain Lion and I do not have the cloud icon on my menu bar. I went to applications in finder and there is no cloud application. I opened Launchpad and there is no cloud application? I do not know where else to find it. I have iTunes match on my iMac and AppleTV and I have cloud on my iPad and iPhone. I am a loyal Apple user and love the products because you can sync them together but this is ******* me off. Where else can I go or what else do I need to download to get this app on my iMac?