Press F1 in the DB editor and you'll get the help files.
If the .bmp file is in the same directory as your program, then you can use what you put. If as you say it's in C:\Program Files\Dark Basic Software\Dark Basic Professional\Media\Bitmaps then you have to either copy the bmp into your project directory or use:
Load Bitmap "C:\Program Files\Dark Basic Software\Dark Basic Professional\Media\Bitmaps\filename.bmp"
I think however that while you have the help files open you should take a look at the
Load Image command because I'm pretty sure that's the command you actually need.
BMP files
are bitmaps, but they are also images and you don't
have to use the Load Bitmap command to load them. If you do, then you'll only have to grab them as images to use them with the other commands.
Load Image bypasses the Load Bitmap and grab stage - but the same location rules as Load Bitmap apply to Load Image.
TDK_Man