To use training board:

Left-click with mouse to place a black piece; right-click to place a white piece.

Click (with either mouse button) on an existing to piece remove it. (With the "show last change" option enabled a change in piece colour is indicated by a dot.)

Save board state with the M+ button, restore the saved board state with MR, and clear the board with C.

Select your options and press "Go"...