This tutorial explains how and when to use the filters that are built into Paint Shop Pro.
Filters modify an image by working with the pixel color values, generally using complex equations.
The Filter Browser allows you to preview filters before you use them. You can access the filters directly just by selecting them form the menus as well as using the Filter Browser. I recommend you play around with the different filters getting a feel for how they work and what they do. Although uses for them may not appear immediately, they are often useful as part of an overall effect - for example, making a neon glow effect by entering some text, using the Blur More filter a few times on it, then entering text again over the original blurred text in a different color. This is the essence of the Neon Glow text effect.