How can I increase a field's width on my form?

I cant change the width of the input fields at all, I have no idea how to use CSS, please see my form below - thanks for your help

https://www.jotform.com//?formID=70377673253966

This could be due to a configuration or theme you have applied to your form; however, the best way to change the field's width would be to inject some CSS code, here's an example:

#fieldID {

    width: 150px !important;

}

You will need to replace the "fieldID" with the real ID from your form and the width value with the needed value for your field. 

This guide will help you to get the field ID: https://www.jotform.com/help/146-How-to-find-field-IDs-and-names 

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

Hope this helps.