How to adjust and move the background strip?:

To Adjust Background strip first get into design mode. Then Click on the background layers. Next, hover over the top or bottom edges and click and drag the mouse up or down to change the size of the layer. To move the layer, hover over it and click and drag the mouse up or down to move it's location.

The position screen allows you to raise the background up/down and change it's height to be smaller and bigger than the chosen background.

Here is how to adjust the background

Step 1: Click on design mode

Step 2: Make sure you are in the background tab (A)

Step 3: Click the Desired Zone (Full Background , Header+Body+Footer, Rows, Columns) (B)

Step 4: Hover over the desired background you want to edit 

Step 5: Click the Position icon (C)

Step 6: Change the values in the height (D) and the top (E) fields to adjust the background.

Note: The Top field can set the position of the background it can take both negative values (To raise it up) and positive values (to lower down)

Tip: You can also drag the edges of the highlighted screen and the highlighted screen itself to adjust the position and the height of the background.