How can I create a sidebar?

I made a sample form with a field used like sidebar, it can be reached here: https://form.jotform.com/61144123079954. 

First you need to get the ID of the HTML element where the field is in, a good way to get that will be following the steps on this guide: https://www.jotform.com/help/146-How-to-find-Field-IDs-Names. 

You will get the ID similar to this #input_13 and you will need to replace the input with id as the code below: 

#id_13{

    position: fixed;

    top: 30%;

    left: 0px;

    background: white;

    width: 20%;

}

This guide will help you to inject the code to your form: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

Hope this helps.