Bitmaps are included in TpX drawings as external files. TpX understands JPEG, PNG and BMP images. Image files can be in the same directory as the parent drawing or in a subdirectory. If inserted bitmap is not in a subdirectory then "bitmaps" subdirectory is created and the file is moved there.
In order to include bitmap in a LaTeX document TpX has to convert it to EPS. Set the path to converter program in "TpX Settings" (Bitmap2EpsPath). It is recommended to use sam2p utility which could be downloaded from http://www.inf.bme.hu/~pts/sam2p/. It is also possible to use the widespread bmeps utility.
Bitmaps can not be used with 'tex' and 'metapost' output formats.