Transparency Versus Opacity

Photoshop uses the concept of Opacity for its layers. When a layer is opaque, it is completely visible and no layers below it can be seen.

The opposite of Opacity is Transparency which is what PhotoImpact uses. To convert from Opacity to Transparency, just subtract the former from 100%.

An opacity of 100% in PS is a transparency of 0%, which are the default states for all new layers. Similarly, an opacity of 40% in PS is a transparency of 60% (=100% - 40%).

In any PS instruction or tutorial you see on the Internet or in a book, it is very simple to adjust the instructions for PI.