By default, form designer looks like:
As well as the parent designer, it contains 4 parts:
 Workspace - the working space. While you add or delete elements, alter their properties - all the changes is presented there.
 
 
 Controls pane - a list of available controls. Exactly from here you can add controls to form.
 
 
 Properties pane - displays properties of the selected control and provides editable text fields for their editing.
 Top bar contains 2 tabs: 
 
 Toolbar - provides functionality for locating controls and saving/cancelling the made configuration.
 Contains 4 buttons:
 
 - allows to align selected control(s).
 
 
 
 - allows to set the same distance between several selected controls.
 
 
 
 - lets to delete a control. 
 
 
 
 - closes the window. Doesn't save made changes.
 
 
 
 - lets to save the current configuration and move it to the workspace of the main (parent) designer.