How to create jqGrid Context Menu?

I am trying to create a context menu on jqGrid (for each row) but can't find how to do so.I am currently using jQuery Context Menu (is there a better way? )but it is for the entire Grid not for a particular row i.e. cannot perform row level operations for it. Please help me in this, thanks.

$(document).ready(function(){ 
  $("#list1").jqGrid({
    sortable: true,
    datatype: "local", 
    height: 250, 
    colNames:['Inv No','Date', 'Client', 'Amount','Tax','Total','Notes'], 
    colModel:[ 
        {name:'id',index:'id', width:60, sorttype:"int"}, 
        {name:'invdate',index:'invdate', width:90, sorttype:"date"}, 
        {name:'name',index:'name', width:100}, 
        {name:'amount',index:'amount', width:80, align:"right",sorttype:"float"}, 
        {name:'tax',index:'tax', width:80, align:"right",sorttype:"float"}, 
        {name:'total',index:'total', width:80,align:"right",sorttype:"float"}, 
        {name:'note',index:'note', width:50, sortable:false} 
        ], 
    multiselect: true,
    rowNum:10, 
    rowList:[10,20,30], 
    pager: '#pager1', 
    sortname: 'id', 
    recordpos: 'left', 
    viewrecords: true, 
    sortorder: "desc",
    caption: "Manipulating Array Data"
  });
  $("#list1").jqGrid('navGrid','#pager1',{add:false,del:false,edit:false,position:'right'});

  $("#list1").contextMenu({
        menu: "myMenu"
    },
        function(action, el, pos) {
        alert(
            "Action: " + action + "\n\n" +
            "Element ID: " + $(el).attr("id") + "\n\n" +
            "X: " + pos.x + "  Y: " + pos.y + " (relative to element)\n\n" +
            "X: " + pos.docX + "  Y: " + pos.docY+ " (relative to document)"
            );
    });