The problem with white balance for a new photographer is they often don't know how to adjust it or even what it is.Take a look at the below photo . . .
Nice photo of my wife, right . . . but now take a look at this photo . . .
MUCH better . . . now take a look at them side by side . . .
The difference is most dramatic when you view the photos side by side. You instantly recognize the photo on the right as having more correct or life-like colors. The problems is when people take their own photos, they don't have a "correct" version to compare against so they often don't even know the colors in their photos are not correct, there is just a feeling that the photos are "not that great" or "just okay". So getting the colors correct in your photos can have a massive impact on how they are perceived. So now that you know this, what does it all mean and how do you fix your photos.
If you are interested in the details of color temperatures and white balance, here is a good explanation from apogeephoto.com but, for the purposes of this tutorial, it's just enough to know that your photo may end up with a color cast that makes the whole photo either too "cool" blue'ish or too "warm" yellow'ish and it can be adjusted.
There are two ways to adjust color balance, either in-camera, or later in a photo editing program.
In-camera is definitely the preferred place to adjust white balance if you are shooting jpegs. If you are shooting RAW, you have much more latitude in the adjustments and can make later during processing and can adjust white balance then but chances are if you shoot in RAW, you already understand white balance and do not need this tutorial.
Unless you have previously messed with your advanced camera settings, chances are you camera is in what's called "auto" white balance where it tries to automatically adjust the white balance for you. And thankfully with modern cameras, most of they are relatively good at doing this on their own. There are some cameras that are better than others and there are certain lighting situations that almost all cameras will get wrong. Some of these are mixed lighting situations, flash photography, shooting in darker sitations (shadows), etc.
If you take a photo and the colors look good (not too much overall blue or yellow) great your done, if not though, it may be time to dust off the owners manual and figure out how to adjust the white balance on your camera. Most cameras let you choose between a number of presets such as sunny, cloudy, flourescent lights, incandescent lights, etc. Give them a try, you may be surprised how much better your photos look in tricky light situations when you get the white balance set correctly.
So what if you didn't get it right in the camera and now it's too late you just want to adjust the white balance if photos you've already taken that you now realize have a color cast. Any image editing program with a darn will have an option to adjust white balance. It my be color color cast, neutral color, or something along these lines.
The two image editing programs I recommend are Picasa, a free download from Google which I recommend for beginners or Adobe Photoshop Lightroom 4 , the premier image editing program for advanced users and well worth it's cost.
In Picasa, choose the 2nd tab and use the "Color Temperature" slider to adjust your white balance. Moving to the left will make the photo blue'er or cooler and to the right, will make it warmer or more yellow. You can also use the neutral color picker to pick a grey (neutral) color is the photo to have Picasa automatically set the white balance for you. This method can be tricky at first.
So go ahead and pull up some of those old photos. Are they too warm or too cool? Now that you know, you can fix it. Give it a try and you may be amazed at how much more professional some of your photos will look.