Changing DesignBoxContent of ['page_main_code']

How can I change de DesignBoxContent of the $_page_cont[$_ni]['page_main_code'] ?

i've tried

$content = PageCompPageMainCode();  // my function returning the content data     
$designBox = DesignBoxContent( _t("_WAZATV_H1"), $content,0 ); // Specifying the designbox
$_page_cont[$_ni]['page_main_code'] = $designBox;

But it keep getting another designbox.

Thanks for help

Ok I figured out how its working!

Because I didnt specify a html file in relation to the Name Index, it as use default wrapper

$_page['name_index'] = [your ID];

Need to create a html of the name of your page file in your template root. (templates/tmpl_yourtemplate/page_[page index ID].html )

In the html file:

<bx_include_tmpl:_sub_header.html />
__page_main_code__
<bx_include_tmpl:_sub_footer.html />

There is not many docs available :-(