Clicking the Position button in the Search group on the Database tab opens up the following window.
At the top of the window we see the Search database drop-down list where you can specify which database you want to search. Following that there are two check boxes. Always remember to check that the correct database is specified! These options were described in the Header Search
The chessboard allows setting up the position to search for.
Clicking a piece in the palette at the top right corner of the window allows you to place a piece of that type on the board. Clicking the empty square in the palette allows you to clear pieces from the board, one at a time, and clicking the cursor icon allows you to drag the pieces on the board around.
clears the board of all the pieces.
sets up the normal starting positions.
sets up the board by pasting a position in FEN/EPD format.
The "Chess960" pane allows you to search for Chess960/Fischerandom positions.
The En passant line
drop-down list allows you to specify if, and then on which file, an en passant capture is possible.
drop-down list lets you select the side to move.
To start the search, press OK.