Simple! Open Bryce 6.  Create a terrain (the mountain thingy) Select and click on the 'E' icon.
This will open the terrain editor. Go to the BRUSH icon on the left hand icon tower. This will open the Brush selector catalogue.
Look forthe import button at the bottom of the catalogue and browse to the location of your new brushes - your .BRP files. Select the file/brush/es you want to import and they should appear in the selection boxes of your catalogue.
Select the new brush you want and away you go!

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All the Woes of a World by Jonathan Icknield aka The Bryster

And in my final hours - I would cling rather to the tattooed hand of kindness - than the unblemished hand of hate...