What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
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.
If I understood you correctly you want to create three fields that are placed in one row. To do that you need to add three text box fields inside of your Form Builder and then you need to shrink them and set their size to 15. Also you can change the name of labels by double clicking on them and then you can enter new label name.
Here is a demo form I made http://form.jotformpro.com/form/51036862865966?
You can also watch this guide to see how to create your first form.
Hope this will help. Let us know if you need further assistance.