well, there are several options-- the rectangle select allows you to select, well a rectangle.. or a square area, the elipse select, alows you to select cicles and ovals, the lasso tool allows you to select an area by traceing it out freehand, then there is the magic wand, which will select an area by colour- this has a tolerance bar that can be adjusted to get just the exact color you want or any colour close, etc, it can also be set to flood- just the imediate area, or global, all of that colour on the page........
all of the select options can be set to replace(defualt) additive, subtract, intersect and invert for even greater options--they all are found in the tool window, with adjustments in the toolbar at the top of the PND work windo