Open an image as shown in section 2.1.2 "Create a simple style using Layer browser". Switch from the Projects pane to the Style Browser, select your first style (e.g. Building Blocks/Simple styles/Random Painter), and drop it onto the Default Layer. Set the properties in the Properties+Preview pane. Now select a second style (e.g. Building blocks/Basic Image Processing/Emboss). Decide whether to add this second style before or after the first style that you applied and then drag and drop the style into the highlighted area of the layer as shown below.

The layer's name will be updated with the new style/filter's name inserted:

Note: Also see section 6.3.1 "Quick key combinations in the Compositing view" to add styles quickly and efficiently.
Note: Styles that are dropped either before or after the previous style do not create new layers. The new style appears in line with the previous one on a single layer like links in a chain. The order of the styles in the processing pipeline can affect the image’s result so experiment with placing a style before or after another to see what effect the order has on your image.
Add a third filter or style by dragging and dropping it before the two previous filters. (e.g. Building Blocks/Basic Image Processing/Majority)
Set the style properties in the Properties + Preview pane to obtain the effect you want.
If necessary you can still adjust the properties for your image as shown in section 1.3 "Adjust result image properties".