You want to put an autonav block in the header area of your home page. After you've added the block, click it and choose "Custom Template", then pick "Header Menu" from the list.

Now the navigation menu will be put on your page as a series of <ul> and <li> tags. You will need to know some HTML/CSS to style these appropriately, although there are tons and tons of tutorials on the internet for how to do this (google "css li tabs" for example). This has nothing to do specifically with concrete5, by the way -- just standard web design.

You want to put the CSS style code into the "main.css" file of your theme (if it's a theme you downloaded from the marketplace, it's in the "themes" folder of your site. If it's one of concrete5's built-in themes, you'll want to copy the theme folder that's inside the concrete5/themes directory to your themes directory (outside of the "concrete" folder).

Hope that makes sense.

-Jordan