The home page is the first page seen when someone comes to your website. You can edit this page in Site Content -> Manage Home Page.
Display Galleries on the Home Page
If you want to simply display a list of available galleries on the home page, select the "Feature Content / Galleries" option. There you can select a section/category to display galleries from on the home page.
Add a Find My Photos Form
You can add a find my photos form on the home page where a customer can enter in their gallery password and be taken directly to their photos without having to navigate to the gallery. To enable this look for the option "Find My Photos Form" option when editing the home page in the admin.