Based on the look of "featured" I would need to create 2 more style
for some articles

how could I achieve this : the checkbox for the "feature" or "top" or "news" selection, and the css style when page displays item.

thx for the help

I suppose you can make it using extrafields. Create extrafield for that purpose, assign it corresponding value and add condition in your item layout to check it and assign css class to item elements.

Or you can create a plugin to add tab in your item edit form and operate item params. And when displaying item - use plugin events to parse these params and assign css class.

Use this code to use K2 extra fields:
[code type=php-brief]
<?php $f=null;
foreach($this->item->extra_fields as $f){
if($f->id == 3) break; //id of the extra field
}
if($f->id && in_array(strtolower($f->value),array('female','male','unisex'))){ //values insterted in the extra field
$class = strtolower($f->value);
?>
<div class='<?php echo $class; ?>' style='position:absolute; top:1px; right:1px; z-index:100;'>
<img src='<?php echo $class.".png"; ?>' />
</div>
<?php } ?>[/code]