Ok, don't worry about F10 - that's just the shortcut on the Mac version I'm using. As long as you have the document layout palette open, you're ok.
When you double-clicked on A-Master A (the one with 'locks') you opened a Master Page. This is ok. If you zoom out, you should see two blank pages side by side. Now anything you place on these pages will automatically appear on any new pages added to your document. You can add an appropriate footer, for example, to the left page, and a different footer to the right page.
When you're done adding these elements, you need to return to your actual document. Double-click the page icon with the A in it to return to it.
When you zoom out to look at the whole page, you should see whatever elements you added to the right hand page appear on this page too (facing pages always begin on the right hand page).
To add more pages, you have a few options. One way is to use the document layout palette. Simply drag the A-Master A page down below page 1. Dragging it to the left of the line will create a new left hand page, or to the right to create a new right hand page.
You can continue doing this if you like, but if you need to add a few pages at once, it's easier to look for the Page menu. The first option in this menu is 'Insert' which brings up a dialog box asking you how many pages you want to add to the document. It also asks you what Master page you want to base it on (you can actually have several master pages in the one document). In this case, you should set it to A-Master A.
Hope this helps!