You can hide layout elements (such as your check box field, but also buttons and other objects) with either a portal or a tab control.
In either case you set fill and line properties so that the portal/tab control is invisible and manipulate it to hide/reveal the layout objects in response to user actions such as entering data in your field.
With a tab control, you give each tab an object name and use a script trigger with a go to object step to select either the tab that shows the objects or the tab that does not show it.
WIth a portal, you set up a single row portal resized to be tall enough so that it can contain the entire layout object and then manipulate the value of the fields used in the portal relationship (or in filemaker 11 you could use a filter expression) to hide/reveal the layout objects. This option does not require use of a script trigger.
Thank you very much PhilModJunk, I've done it with a portal and it works.
It works very well on FileMaker but on the Web, I've to save the changes after I can see the invisibility/visibility of the field...
Is there some way to see the change with the field before saving the changes?
I don't have a lot of experience with IWP, so someone else may know of a way, but since your browser can't update until you commit the data, I don't see a way to do this.