The white pieces has been arranged on a QWERTY keys and the black ones on the bottom row of your keyboard, similar to the way they are arranged on a chess board. There are, of course, four of each piece: Black piece on white square, White on white, Black on black and White on black.
For simplicity the pieces standing on white squares are in the place of lower case letters and the pieces standing on black squares are in the place of upper case letters. To type any piece on a white square, with CapsLock off, simply press the relevant key. To type the same piece on a black square hold down <Shift> as well.
The Keys M and m produce an empty black square, <Space> is an empty white square. This arrangement makes it easy to include the white square chess pieces in text since when typing large amounts of text CapsLock is usually off.
There is also a border included in the font which can be used to finish off chess diagrams. Again it has been arranged so that it is easy to remember and use: if you use the numeric pad to type the border characters then it is easy to remember that for example, the top left corner piece is key 7 and that the right hand border piece is key 6 etc.
This font is supplied with a detailed manual.