RSS Feed Problem

My wordPress site is in the construction stage. I put a Subscribe button on, and tested it. I used it to add the feed to my Google homepage. The initial “Hello, World” post showed up under the blog title on my Google homepage. But I can’t get that to update. I’ve deleted the Hello, world post, and created a real post. It won’t show up in the feed on Google, and the Hello, world (deleted) post is still listed as the only post. I then deleted the feed gadget from Google, and used the subscribe button on my site to again put a feed on the Google page. I also cleared the FireFox cache. But the “new” feed still shows Hello, world, even though that post was deleted, and does not show the new post. Any suggestions? Please be un-technical; I’m out of my depth here!