WordPress does not always show a "Home" button in the menu by default. If you have just started your site, you may need to create a link which points to your homepage and add this to your main menu. Follow the steps below to do this:
1. Go to Appearance > Menus in your dashboard:
2. Click the Custom Links tab:
3. Set the options to the following:
URL: / (a forward slash)
Link Text: Home (or anything else you want to call it)
Now click "Add to Menu" and this will add the "Home" item to your menu.
4. You can now drag the "Home" menu item into the position you'd like. Then click "Save" and you're done!
The animation below shows the process: