Magento URL rewrite management
There is URL rewrite management under Catalog section. You can set a rewrite rule for any category to point to any web url.
So, you create a category, find the link to it and create a URL rewrite rule ( Catalog->URL rewrite management section in the backend)- to redirect it to another URL.
Guide from magentocommerce:
How to add static page in Magento navigation menu
Goto Catalog --> Manage Categories, and create a new category with display mode "static block only"
Insert page content in the "description" field
How to add "Home" button to Magento menu
Please open System - Configuration-->Custom Menu-->General section and find "Show the link "Home" option.
Also you can create a category called HOME and then use the URL rewrite management to create a link to your store.
This is a guide on how to add any page to the Responsive Magento Custom Menu.
Custom Menu extension has some interesting and powerful functionalities like ability to customize number of columns, apply a static block, Right-to-Left format support and feature "Split categories left to right into columns".