Start up Bryce, create any object (sphere for example). Select the sphere, click on the M in the little stack of options that appears beside it, which takes you into the materials lab. In the mat lab, put a bead in the first column against the diffuse option, so that a default texture appears on the right. Now click on the little P under the texture, to turn it into a picture object (you should get leo as default), then click on the bead above leo's head, to take you into the picture editor. Click on an empty square in the pic editor; this opens an explorer window. Find your .bmp file and double-click on it to load it in. Create a bump channel for it if you want to, then click on the tickmark to close the pic editor. Back in the mat lab, adjust the settings on your new material as required, then click on the little right-facing arrow to the right of the preview window. This will open your material library; decide which category you want to add your new material to, then click on add at the bottom of the window, give the mat a name and description, click the tickmark to save it, click the tickmark to close the material library, and Hey Presto! your .bmp is now a Bryce .mat!