passing parameters to server side code on jqgrid edit row
===

I try to use JQgrid and eidt my objects. But I don't know that how to pass parameters to server side code. Here is my jq codes:

     jQuery("#tblList").jqGrid({
                url: 'CityList.aspx/GetList',
                editurl: 'CityList.aspx/GetList',
                mtype: 'POST',
                datatype: 'json',
                postData: { searchString: '', searchField: '', searchOper: '' },
                ajaxGridOptions: { contentType: "application/json" },
                serializeGridData: function (postData) {
                    var propertyName, propertyValue, dataToSend = {};
                    for (propertyName in postData) {
                        if (postData.hasOwnProperty(propertyName)) {
                            propertyValue = postData[propertyName];
                            if ($.isFunction(propertyValue)) {
                                dataToSend[propertyName] = propertyValue();
                            } else {
                                dataToSend[propertyName] = propertyValue
                            }
                        }
                    }
                    return JSON.stringify(dataToSend);
                },
                jsonReader: {
                    root: "d.rows",
                    page: "d.page",
                    total: "d.total",
                    records: "d.records"
                },
                colNames: ['Id', 'Şehir Adı'],
                colModel: [
                    { name: 'CityId', index: 'CityId', hidden: true },
                    { name: 'Name', index: 'Name', width: 400, editable: true, edittype: 'text' }
                ],
                ondblClickRow: function (id) { alert("You double click row with id: " + id); },
                pager: '#tblPager',
                rowList: [10, 20, 30],
                sortname: 'CityId',
                sortorder: 'desc',
                rowNum: 10,
                loadtext: "Yukleniyor....",
                shrinkToFit: false,
                multiselect: false,
                emptyrecords: "Kayit Bulunamadi",
                autowidth: true,
                shrinkToFit: true,
                height: "400",
                rownumbers: true,
                //subGrid: true,
                caption: 'Şehirler'
            }).navGrid('#tblPager', { add: true, edit: true, del: true, reload: true });

        });
        jQuery("#tblList").editGridRow(rowid, properties);

I am new on jqgrid. Can you tell me how can I edit my records?