To add a home link to the Menu, follow the next simple steps:
1. Backup your files.
2. Head to Appearance>>Menu
3. Create a new Menu
4. Add a custom link called Home and specify the address of your home
5. Add more menu links by adding pages or categories if you want
6. Save the menu and select the newly created menu as primary navigation menu and save again
Please check out for the video tutorials on net for more clarification. WordPress 3.0 Custom Menus Tutorial.