Is it possible to add another field so if the user answer Yes, the fields will be added if no the questions fields will not show.

2) Is it possible to add questions and fields only if the answer is for example "yes" in a first field ?

If the answer is "no" then we dont' have the fill these questions so we don't have to add the question to the user.

Hi Bruno,

Thanks for reaching out to Jotform Support. Just to confirm, do you want to add a Question field so that when the user answers Yes, all the required fields will be shown while when the user answers No, all the fields will be hidden? If so, this is possible by using Show/Hide Field conditional logic. Check out the steps and screencast below to see how it's done:

Add another field that will let your users select a Yes or No. In my example, I added a Single Choice element.

Now, we will set up a condition that will hide or show the fields depending on your user's answer.

1. In Form Builder, in the orange navigation bar at the top of the screen, click on Settings.
2. Choose Conditions on the left side of the page.
3. Add a new condition and select the Show/Hide Field option.

4. Set up your condition in the next window. You can check my sample condition below:

5. Lastly, click Save.

Here's the result:

You can also check my demo form to test it.

If that’s not exactly what you’re looking for, can you explain a bit more so I can help you better? 

Give it a try and let us know how it goes.

Ok thank you, it's like what I want ! Perfect !