Well, what I want is simple. I need to add one div every 3 paragraphs. Remember that these paragraphs will be in another div (in case it would be the content div).
It is similar to that of site , where it is found the announcement.
It would look like this:
<div class="conteudo">
<p> </p>
<p> </p>
<p> </p>
<div class="anuncio">Div inserida</div>
<p> </p>
<p> </p>
<p> </p>
<div class="anuncio">Div inserida</div>
<p> </p>
</div>