To get started, select Open from the File menu and navigate to your image file. You've got your image open in Photoshop.

Now is a real good time to save the image. It's generally best to work on a full-resolution image until you're ready for the final reduction in size and resolution, so save it (wherever you like, but make sure you know where) as a Photoshop document (.psd), no compression.

Opening an image in Photoshop. If the image originates from a scan, it may appear upside down -- you'll need to correct that.

Now, after every step, if you are sure you like what you have done, save the file. That way you won't lose work when the computer crashes. Cmd-S (Mac) or Ctrl-S (Windows) is the easiest way to save quickly. You can also save multiple versions of your image via the File | Save As menu. In fact, its a good idea to save a copy of your original file at the beginning of your work. This way, if you mess up big time, at least you can start over from your source material.

If the picture appears sideways, upside-down, or reversed in the Photoshop document window, pull down Image | Rotate Canvas, then select the appropriate change to apply.

Now that the image is correctly oriented, you may wish to crop it-remove the unwanted area around the part of the image you want to show.

Now select the Crop tool on the tools palette, which looks two letter "L"s overlayed.

Place the cropping cursor at one corner of the image and click-and-drag diagonally, creating a selection marquee around the part of the image you wish to keep. Once you've created a cropping selection, you can adjust it by dragging the handles on its edges.

The little boxes at the corners and along the edges of the crop marquee allow you to grab and make adjustments to your crop before you finalize it. When you are satisfied with the crop you've selected, press the RETURN key, or under the Image menu, select CROP.

If you get nervous, you can get out of crop mode by hitting the Escape key on your keyboard.

Your first step is to adjust the "levels." Under the Image menu, pull down Adjustments | Levels.
This will bring up the Levels adjustment window, with a representation of how the tones are distributed throughout your image (a histogram), with the dark tones on the left. You can move this window around, so it's not obscuring the important parts of your image (just grab it by its top bar, click, and drag).

Often in digitized images, the darkest tones will be a little above full black, and the lightest a little darker than full white. This is represented in the Levels window by the gaps between the edges of the window and the endpoints of the histogram.

To start, grab the little triangle under the left end of the graph, and slide it toward the right, until it's just under the first part of the tonal information in the histogram , repeat this for right triangle.

You can adjust the midtones by the middle triangle, when you are happy hit OK.

Save your image.