Usually, you can simply select the Red Eye tool and click on the red eye to fix a photo. Sometimes, a bit more effort is required, for example, when the rest of the face has a reddish tinge, the tool has a more difficult job deciding what is a red eye and what is skin.
Simple case:

1. Click on Red Eye Reduction on the Tools bar
2. Click on the red part of an affected eye for a fix (if the eye is small, first zoom in to enlarge it).
3. Repeat for the other eye.

Fine tuning:
Click on the Red Eye Reduction tool. On the Magic Wand toolbox that appears there are three sliders will be displayed that control the Red Eye tool:

• Threshold: the range of the pixels to be changed according to color and tonal values. The higher the threshold, the more surrounding pixels will be effected. If the standard settings for Red Eye cause colour to leak outside the eye area, reduce the threshold value.
• Power: the strength of red channel reduction. All red in the selected pixels is reduced to same level as blue and green (actually, the minimum of the blue and green channels) and then Power is also subtracted. The higher the value of Power, the less red the resultant image will appear.
• Red: Limits the affected pixels according to how relatively red they are. Set to a high value, less of the pixels within the selected range will be included when the tool is used. Set to a low value, most of the pixels will be affected. Technically, the tool is applied to all pixels where the red level is greater than the minimum of blue/green channels plus the Red Range value.

Open your colour image. Go to the top menu

1. Select Image
2. Select Adjust
3. Select Greyscale.

Open your picture. Go to the top menu

1. Select Image
2. Select Image Size
3. Select the desired measurement from the dropdown menu (ie cms, mms, etc), then type in the size
4. Click 'OK'

Open your picture. Go to the top menu

1. Select View/Layers
2. On the sliding scale of the layers palette, change the opacity until it is the desired opacity