I can see the comment box at your posts. Did you fix it? The comment function inherits from Twenty Seventeen parent theme. Winter Solstice child theme only changed the front end style.
There are many ways to do this but the easiest way without installing a plugin (page builder) is using table. You can find table button on WordPress editor, or simply use below code to create a table with two columns:
<table>
<tr>
<td>your text goes here</td>
<td>your form goes here</td>
</tr>
</table>
