If you are not familiar with the general use of ADE functions then you might want to read the main manual.
http://www.mediafire.com/download/8rp6jr7en9xwdls Although this is for an earlier version all the main functions are present. Meantime to create an exclusion rectangle click the yellow square toolbar button
This changes the cursor. with the left mouse button pressed draw a rectangle from top left to bottom right covering the area you which to make exclusions in. When you release the left mouse button the property grid will open
Select the exclude flags you want active and change the value from false to true
Then click Save
Note that the cursor will stay as a cross so you can draw more excludes if you wish, To go back to the regular cursor press the Esc key
We are aware that not all flags work all of the time but you can try.
Try not to overlap exclusion rectangles since that can also give unexpected results