Now with the Magic Wand
click on the White Milk area.
Cut it away
It should look like this
Now using the fill tool, Shown,
Be sure the top box it white. You place the mouse over the color you want
left click is the top color, right click is the bottom
Fill the glass with white
Select None
(CTRL-D)
on the layer pallet, click for a new layer
The top blank layer needs to be moved under the image layer
Right click ON the layer. Arrange - Move Down
Now click the magic wand on the blank layer
Selections - Modify - Contract
2 pixels
Invert Selection
Notice the small area to fill the black.
This will make an even box around the image