Bltplayer does a bit block transfer of the player sprite(s) to the game window.
rec.top = the top pixel location of the source or destination device context. (DD surface / game window)
rec.left = the left pixel location of the source or destination device context. (DD surface / game window)
rec.bottom = the bottom pixel location of the source or destination device context. (DD surface / game window)
rec.right = the right pixel location of the source or destination device context. (DD surface / game window)
rec.bottom - rec.top + 1 = the height of the section you want to do the bit block transfer of/to.
rec.right - rec.left + 1 = the width of the section you want to do the bit block transfer of/to.
Hope that explained it for ya.. If not, feel free to post more questions.