The Magic Wand tool lets you select an area of a bitmap based on color. You can specify the color range, or tolerance, for the magic wand tool's selection.
With the bitmap selected, from the Bitmap Edit toolbar:
Enter a low value to select colors very similar to the pixel you click, or a higher value to select a broader range of colors.
Use Shift and Ctrl (command in Macintosh) to add or subtract areas from the existing marquees. (A small + or - appears near the bottom of the cursor to indicate Add or Subtract.)
Marquee created with the Magic Wand tool |