Start by opening a new document in CorelDraw and make two overlapping rectangles, filling each with a solid color, one red and one blue for instance. One of those two colors will appear in front of the other since each will contain a solid, opaque color.
There is a group of tools in the Toolbar whose default tool is the Blend tool, but which also contains the Contour tool along with several others, including the Transparency tool. The icon resembles a wine glass.
Make sure the front rectangle is selected then click on the Transparency tool in the toolbar. You will see the Properties bar above change, and in it you will see a rectangle with the word None inside with an arrow to the right that opens a dropdown menu. Since you have filled the selected rectangle with a solid color, choose Uniform from the dropdown menu, indicating that you want to apply the transparency to a uniform fill.
The box to the right of the dropdown menu displays the word Normal. This, too, is a dropdown menu, giving you a whole set of options regarding how you want the transparency to affect the solid color. For now, leave it set at Normal.
To the right of Normal in what is called the Transparency Operation dropdown menu is a slider with a box to the right of it showing the degree of transparency with 50 percent being the default. The rectangle to the front has changed as a result of using the Transparency tool at these settings—whatever solid color it held has had its opacity reduced by 50 percent. On the white background the color is now half of the opacity of the original color. Where it overlaps is also half of the opacity of the original color, but now the color of the other rectangle is bleeding through, creating a new color mixture. That’s a pretty simple operation producing a pretty significant effect.