Go to Blogger.com, log in to your account and click the "Design" link next to the site you want to edit. Click the "Add a Gadget" link in one of the available layout sections. A pop-up window appears.

Blogger blogs don't come with menu tabs as a standard template feature, but you can use the workaround solution of adding menu tabs to your blog's home page with the Blogger Pages gadget or the Link ...