JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Once on the edit mode of your form:
1) Go to Preferences
2) Form Style
3) Form Width
There you can increase the number to make it wider:
If you need to increase the width and height of your fields, you can do it using the Form Designer:
1) Click on Designer:
2) Click on one of your fields, and the Text Box fields option will appear:
Here are some guides that may be of your interest: http://www.jotform.com/help/300-Form-Designer-Tutorial-Let-s-create-fantastic-forms-
Let us know if you need more help, we will be glad to assist you.