To take a Christmas tree silhouette picture, start by positioning your camera to capture the whole tree in the frame. Make sure to get the shape and height of the tree as well as any decorations or ornaments. Use a tripod to ensure that your camera is steady. Next, adjust the exposure settings to minimize background light and increase contrast. This will help the tree stand out against a dark background. Finally, experiment with different angles and lighting to find the best composition for your shot.