Creating a custom content type

Creating a new content type is very simple;…it can be done through the web browser or through SharePoint Designer.…So I'm looking at a publishing portal right now, and I have just recreated…this as a default publishing portal with all the same setting as they are…right out of the box.…And sometimes it's actually useful to reverse engineer the existing situation.…So we know that when we create a new page in this kind of site that we will have…the ability to choose from a few exiting Page Layouts because SharePoint…actually gives us a few of them just with the default site template.…

So what are these, what is actually going on here?…I can see that I have got Page Layouts for Body only, Image on the left that I…can change to, it gives me a slightly different layout, back to the page section…of the ribbon, image on the right, gives me another one, and so on.…But where are these?…I'm going to go to my Site Actions, Site Settings on the site.…I want to find is the Masterpages and the Page Layout gallery.…