First thing to make sure when you are using a multiple page setup, is to make sure you are enabling editing of the right Page. In your case I would say that is the content Page (second HTML page), since that is where your (editable) Components are on.
So then you need to make sure that the XPM Page markup is only available for that second page. When you have multiple XPM Page Settings, you will definitely get strange (unwanted) behavior.
Furthermore, when you want to edit fields, you need to make sure that you have both the
Start Component Presentation and the
Start Component Field markup on your Page, and the
Start Component Presentation markup need to be around the
Start Component Field markup. Each markup needs to be in their own HTML container (like a
span tag) and of course the markup needs to be valid.
Last thing I can mention is that all of this information needs to be on the page at the right time, as XPM will index your page and inspect the available markup when it loads the page (which is right after the HTML DOM is loaded). Any markup you add afterwards via AJAX or something, will be too late for XPM, and thus those items will not appear editable.
This all being said, I hope you have some pointers to get your problem solved, if not, by all means edit your question and provide more detail, so we can answer it in more detail too.