For new WordPress users trying to set up a website and using the former as a CMS, this is usually among the first questions asked. This is really easy. In fact the WordPress Codex has it all written down step by step here.
Then usually, the next question after having done the steps is, “I have 2 Home pages now. How do I fix this to show just one?”
Under “Troubleshooting Themes” of the tutorial explains a bit on why this happens. If you’re not patient enough to learn the internals of WordPress or manually edit a template file, the quick solution to this problem is a plugin.
Search for WordPress plugins that deal with Page Management. I use pageMash to do this. It’s not very updated but it still works up to 2.8.4 quite well. If there are more updated (compatible and tested with 2.8.4 version) plugins that deal with page management I would suggest you install that instead.