In the Tools option of the main menu you have several additional editing options:
Add/ Remove : you can add/ remove layout elements – Logo, Site Title, Site Description, Menu, the Meta information of the Posts, the Post Utility section, Sidebars or Footer Link (for PRO users).
Dimensions: set the exact dimensions of each element. This tool can be used for more accuracy than by using the Green Knob.
*Note: If you want to change the dimensions of a parent element, you cannot make it smaller than its child elements. Change the dimensions of the child elements first and then adapt the parent element.
The padding expands the space around the content to the border of the element.
The Master Opacity section sets the opacity of an element and all its child elements.
If you want to set opacity just for an image you must edit the images in an outside program using an image format that allows transparency (.PNG image files).