One example of a situation where it may be necessary to adjusting colour balance is when photographs are taken under artificial light made using film designed for daylight. Artificial light, especially from incandescent tungsten light bulbs, is often rather yellow. (This is because the white-hot tungsten filament is much cooler, at about 3000K, than the surface of the sun, at about 5000K). Note that digital cameras usually have an 'automatic white balance' feature that almost eliminates this problem, but the automatic white balance can itself cause false colour rendition if the picture includes large areas of the same colour. Red sunsets for example, might look too pale because the automatic white balance always tries to eliminate any overall colour bias in the picture. The following photo was taken in the Paris metro under fluorescent lighting which often gives photos a green cast. 

As usual, Paint Shop Pro offers you the option of adjusting the colour balance automatically (Adjust > Automatic Colour Balance) but don't even try it because it won't do a good job on this photo (I already tried it). Instead, adjust the colour balance manually with Adjust > Colour Balance> Colour Balance. Make sure that 'midtones' and 'conserve luminosity' are both selected, then slide the colour sliders until the metro station has a grey tint rather than green or brown (it may be helpful to think of 'brown' as being like a dark red). I find that it is usually not necessary to change the balance for highlights or shadows, only for midtones. As you try to get the best colour balance possible, check the skin tones of the rather attractive French woman, since skin tones are a good reference for colours. Save your picture once you have done your best to correct the colour balance, and remember that Paint Shop Pro cannot do miracles and that sometimes the result will be less than ideal. A photograph taken underwater without flash, for example, is always likely to be lacking in red, even after colour adjustment, since it is likely that all the red light will have been absorbed by the water.

Another good option for colour balance is Adjust > Colour Balance > Grey World Colour Balance. This adjust the colours until the average of all the colours in the image is grey - this doesn't mean that everything is grey, just that the image will not be dominated by any one colour - it won't have an overall 'colour cast'. This is a good choice therefore for most photos but would be a very bad choice for a photo of a sunset, for example, which SHOULD have a red or orange cast. Open the same picture, copying the picture above and pasting it again into Paint Shop Pro if necessary, then try using the Grey World Colour Balance adjustment on it. You will be invited to specify a 'colour temperature' for the picture - I suggest a temperature of about 5000K for photos taken in artificial light or 6500K for photos taken in daylight (that's the temperature of the surface of the sun, the same as 6227°C).