动态更改dojo datagrids结构

我用来创建网格的javascript代码

function setgrid(){
    var gridLayout = [];
    var key,i;
    for(i = 0; i < 10; i++) {
        key = i + "";
        gridLayout.push({
            field: key,name: key,editable: false
        });                       
    }

    // create a new grid:
    billsGrid = new dojox.grid.DataGrid({
        query: {},//store: store,clientSort: true,rowSelector: '20px',structure: gridLayout,columnReordering: true
    },gridContainer);

    // Call startup,in order to render the grid:
    billsGrid.startup();
}

和HTML：

<div id="gridContainer" style="width: 650px; height: 600px; border: 1px solid silver;" />

如何更改网格以使用5列的新布局？