update readme.md

README.md

@@ -4,3 +4,44 @@ Starter project for a chess-based TDD exercise
 Install with `npm install`
 Run tests with `npm test`
 Start program with `npm start`. This will host a server on `localhost:3000`
+
+
+Guide to the code
+=================
+
+## Board
+
+When a board is created it initialises a 2-dimensional array of length 8.
+That is, an array of 8 arrays, where each array inside has a length of 8.
+
+These represent rows and columns.
+
+So, to select the first row you can do 
+`let row1 = board[0]`
+And to get the second square of that row:
+`let square = row1[1]`
+Or, in shorthand:
+`let square = board[0][1]`
+
+`Board` then has the following methods to use:
+`setPiece(square, piece)` places the given piece on a square returns nothing.
+`getPiece(square)` returns the piece on a given square, if one is there.
+`findPiece(pieceToFind)` will return the square that the piece is on, if it is on the board.
+`movePiece(fromSquare, toSquare)` will move the piece on the fromSquare to the toSquare.
+
+## Square
+
+Squares have two properties: `row` and `col`.
+
+Squares can be made one of two ways (I'm not really sure why...)
+`let square1 = Square.at(0,1)`
+OR
+`let square2 = new Square(0,1)`
+These are equal. You can check like this:
+`square1.equals(square2)`. This will return a boolean (in this case, true.)
+
+## Pieces
+
+pieces have one method: `getAvailableMoves(board)`.
+This method must be given the current board (so that it can know which moves are available!)
+it returns an array, which is a list of `Square`s that are available to be moved to.