Size and position can be edited in two ways:
1. The size can be change by holding left click on the handles  of and element and draging them in the direction you wish. And the position can be changed with "Drag and drop", wich means you can hold left click  on an element and move it where you want.
2. Go to Edit  ribbon and click on Size and Position , make sure you have the element to be edited selected. Here you have a better way to edit size and position: "X:"  is the vertical coordonate and "Y:"  is the horizontal coordonate , "W:"  is the width of the element and "H:"  is the hight of the element. You also have arrows  for better precision in moving your elements.