adding color to black and white photos

Okay, I see now. You can't do this with iPhoto. iPhoto is primarily an image organizer, with a few editing tools for convenience. What you need is a true image editor. I highly recommend PhotoShop Elements 4 for Mac. It's reasonably priced and very powerful. I have it set as my external editor so that when I double-click a photo in my iPhoto library it opens in PE for editing. When I Save, my edited version is saved back into my iPhoto library.

Check out this Elements User Tipsheet. If the link works for you, view the fourth and fifth videos, which show how to change the photo to black & white, then paint the color back to selected areas. These and the other videos on that page give you an idea of what can be done to tinker with color using PE.

To add to Smtr's recommendation of Photoshop Elements 4 for Mac, it has about 80% of Photoshops capability at 1/7 the cost. You can do some quite advancedediting with it. Amazon.com often has deals on it for about $80. If you happen to be in the market for a scanner, Canon bundles PSE4 with many of it's scanners, some not much more that the cost of the software alone.

Do you Twango?

TIP: For insurance against the iPhoto database corruption that many users have experienced I recommend making a backup copy of the Library6.iPhoto database file and keep it current. If problems crop up where iPhoto suddenly can't see any photos or thinks there are no photos in the library, replacing the working Library6.iPhoto file with the backup will often get the library back. By keeping it current I mean backup after each import and/or any serious editing or work on books, slideshows, calendars, cards, etc. That insures that if a problem pops up and you do need to replace the database file, you'll retain all those efforts. It doesn't take long to make the backup and it's good insurance.
I've written an Automator workflow application (requires Tiger), iPhoto dB File Backup, that will copy the selected Library6.iPhoto file from your iPhoto Library folder to the Pictures folder, replacing any previous version of it. You can download it at Toad's Cellar. Be sure to read the Read Me pdf file.

Welcome to the Apple Discussions.

Yes. In iPhoto 6 you can use the Effects Panel to change a color photo to black & white. (or sepia, or a few others) Then use the Effects sliders to boost the Brightness, Contrast, or Exposure.