pass string from jquery to php

pass string from jquery to php

Can any 1 give me hints on how :
to send variables (array or string) from jquery to php...
I use jquery to copy/duplicate <select> box, I set to them different names and id's, and i need a way to pass the new name <select name=" ???">  to my index.php in order to do some calculations.

Is this bad way to do the job? Any ideas?

As far as i can see the best way would be to get <select name="???"> as soon as it's generated and that means using ajax (im not fammiliar with ajax nor js :( and i feel like idiot) .... Other way i think is to use aditional button that has function in same script to post the values (or one string value ready to be exploded in php)

This is how far i got :
        <script type="text/javascript">
            <!--//
            var i=0;
            var str=null;
            var tablenames = new Array ();
            var namevar=0;
            $(document).ready(function(){
                $("#add").click(function(){
                    namevar = (Math.floor(Math.random()*101));
                    var idvar = (Math.floor(Math.random()*101));
                    var newselect = $("#start").clone();
                    $(newselect).attr("name",namevar);
                    $(newselect).attr("id",idvar);
                    $(newselect).appendTo($("#destinations")).before("<br />");
                    tablenames[i]=namevar;
                    i=i+1;
                });
            });
            function vrati(){
                for (var i=0; i<tablenames.length; i++) {str = str + tablenames[i] + "&" }
                $.post('index.php',{
                    retstring: str}
                ,function(data)
                {
//                    alert(data);
                })
            }
            document.getElementById("add").onclick = function(){
            }
            //-->
</script>