If fields are the building blocks of the form, then consider the sections (or the left menu) the structure of the registration form.
What Sections are Visible on the Form?
Anything between and including HEADER and FOOTER and where visibility conditions are met are visible sections on the form.
How to Edit a Section
1. Click on the Section you wish to edit from the left menu.
2. Click "Properties" (the link beside the section name at the top) to reveal a table that will allow you to edit the section name, show/hide the subtotal box, change the background color, make the section visible/invisible, and/or delete the section. (as shown below).

3. Click Edit in the second to last column and make the changes you want. Then click Update once your changes are completed.


Visibility Conditions
While editing a section's properties, select the Add Visibility Conditions button to launch a new pop-up window. Create a condition(s). The section will only appear on the form if the condition is met. If it is not, the section will not be visible.
Note that required validation will be ignored upon submission for fields within a section that is not visible.