2 div style for Each Post

WordPress already creates specific classes for post IDs, page types, and even whether the page is even or odd. You should be able to see the source or inspect the element using firebug. You should be able to style the theme accordingly using your style.css file

i really don’t know how any tutorial ?
or anyone can update this code to display
first li
<li><div class="writers"><span class="article_title">
and second li
<li><div class="writers1"><span class="article_title">

In the foreach you could probably create an increment to produce those classes. For example:

$count = 0;
foreach ( $var as $v ){
     //Increment each iteration
     $count++;
     $output_buffer .= '<li><div class="writers' . $count  . '"><span class="article_title">';
}

Something like that should work.

oups i guess you understand me wrong

the final output would be

[code moderated - please use the pastebin]

sorry for bothering

You should probably try it out first. It adds a value of 1 to the variable $count for each post in the array.