I currently have a cshtml/javascript/jQuery webapp and I want to insert a `<td>` inside a `<tr>` inside an existing `<thead>` of a `<table>`. I don't know how can I insert `<tr>` inside an existing `<thead>`. I know how to create one and fill it, but how can I insert new lines?

I want to insert:

```
<tr class="ligne" style="height: 0px; background-color: white;">
    <td style="border-bottom: black 1px solid; padding-bottom: 0px; height: 1px; padding-top: 0px;" colSpan="6"/>
</tr>

```

I want to insert it just under the selected line, below:

[![enter image description here](https://i.stack.imgur.com/JSyFB.png)](https://i.stack.imgur.com/JSyFB.png)

How can I achieve that?