$checkvisits = "SELECT firsttime FROM churchushers WHERE user=$user";
$res = mysql_query($checkvisits);
if ($res) //i.e. if the query returns success, fetch the result
{
$crude = mysql_fetch_row($res);
if($crude[0] == 1) //in this case it is "an old user"
{
//go ahead and redirect appropriately
//header("Location:blah_blah" );

}
else if ($crude[0] == 0) //in this case "new user"
{
$sqlupdate ="UPDATE churchusers SET firsttime = 1 WHERE user=".$user;
mysql_query($sqlupdate ) ;
//redirect appropriately
//header("Location:blah_blah" ) ;
}
}

<input type="submit" value="Send" name="button1" id="hello" onclick="alert('hello');">