Send Like/Dislike to database with ajax
===

I have a little problem, I need to send an ajax request to a file.
Here is my HTML File (index.html)

    <a id="like" href="./?act=like&id=24" title="Nobody likes this post!">Like</a> &middot; <a id="dislike" href="./?act=dislike&id=24" title="Nobody dislikes this post!">Dislike</a>

And my like.php file:

    <?php
    if(!is_logged()) {
    header("Location: ./?act=Home");
	die();
    }
    $uid = $user['id'];
    $id = $_GET['id'];
    if(isset($id)) {
    $query = mysql_query("INSERT INTO ld (auth_id,post_id,val) VALUES ('".$uid."','".$id."','1')");
    if($query) {
	header("Location: ".$_SERVER['HTTP_REFERER']);
    } else {
	echo "Contatta l'amministratore riportando l'errore 101";
    }
    } else {
	header("Location: ./?act=Home");
    }
    ?>

And my "ld" table:

    == Struttura della tabella ld
    
    |------
    |Campo|Tipo|Null|Predefinito
    |------
    |//**id**//|int(5)|No|
    |auth_id|varchar(5)|No|
    |post_id|varchar(5)|No|
    |val|varchar(1)|No|
    == Dump dei dati per la tabella ld
    
    |5|4|1|1
    |6|4|1|1
    |7|4|1|1
    |8|4|1|1
    |9|4|1|1
    |10|4|1|1
    |12|4|1|1
    |13|4|1|1
    |14|4|1|2
    |20|4|15|1
    |23|5|17|1
    |29|4|17|1
    |30|4|18|1
    == Struttura della tabella ld
    
    |------
    |Campo|Tipo|Null|Predefinito
    |------
    |//**id**//|int(5)|No|
    |auth_id|varchar(5)|No|
    |post_id|varchar(5)|No|
    |val|varchar(1)|No|

I really don't know how to send an ajax request, and I have also tried to learn ajax but no way, I can't understand it :/