After several days, finally I found how to make ajax call from my wordpress site, I hope that it will help those who have had this problem:
first, I was created a post inside a wordpress whit this html code:
<section id="main">
<table id="tng" class="datagrid">
<thead><tr><th colspan="3">
Sample ping App
</th>
</thead>
<tbody>
</tr><tr>
<td width="50%" align="right"><b>Host or IP:</b></td>
<td><input id="ip" size="20" value="" ></td>
<td><button type="button" onclick="PING()">Ping</button></td>
</tr>
</tbody>
</table>
<img id="image" src="spinner.gif" alt="wait..." style="display: none;">
<br>
</section>
<section id=food>
<h3 id="notification"></h3>
</section>
As you can see the only important thing is the onclick event for the button that calls de functionPING()
