Open and Image. Choose Image>Adjustments>Black and White.
You will now have a black and white image. To adjust the intensity of the black and white tones move the color sliders back and forth under Custom Preset. Look at your image to see how the sliders affect it as you move them.
Next, change the Custom Preset to one of the Filter choices from the Preset Drop Down Menu. See how each affects your image differently.
After deciding on a Custom or Filter Preset you can use the color sliders to fine-tune your shading. Or you can hold your cursor over the image (cursor looks like an eyedropper) and then click and drag on the different areas of the image that you want to make darker or lighter. Dragging left makes them lighter and dragging right makes them darker.
If you want to color tone your image to sepia, or blue, or magenta, etc., simply check the Tint Box at the lower left corner of the BW dialog box. Then move the hue and saturation sliders back and forth to choose a tone.