you can find your answer right in the docu:
<table class="easyui-datagrid" style="width:400px;height:250px"
data-options="url:'datagrid_data.json',fitColumns:true,singleSelect:true">
<thead>
<tr>
<th data-options="field:'code',width:100">Code</th>
<th data-options="field:'name',width:100">Name</th>
<th data-options="field:'price',width:100,align:'right'">Price</th>
</tr>
</thead>
</table>