Someone correct me if I am wrong, but the notation most people use on this site goes as
follows:
a-h: The files (columns of squares running along the board).
1-8: The ranks (rows of squares running across the board).
These are numbered respectively rightwards and upwards FROM WHITE'S POINT-OF-VIEW.
So White's king starts on e1, Black's pawns all start on the 7th rank and both queens' bishops
start on the c-file, for example.
The pieces are:
K = King
Q = Queen
R = Rook
B = Bishop
N = Knight
The notation for a move looks something like this (without the brackets, I inserted them to
indicate the different parts of the code):
M (...)Abc(xD)ef(+/++/🙄(!/?)
where M is the move number and ... indicates a move for Black (otherwise for White)
(eg Black's 1st move might be 1 ...e5 and the next pair of moves could be 2 Nc3 d5)
where A is the piece being moved (omitted if a pawn is moved)
bc is the file and rank (eg f5) from which the piece moves (rank, file or both often omitted,
unless there is ambiguity)
ef is the file and rank to which the piece moves (omitted only if the move is a capture, and
the identity of the captured piece removes any ambiguity, eg QxQ)
x indicates a piece is being taken
D is the piece being taken
+ means 'check'
++ sometimes means 'double check', sometimes means 'checkmate'
# means 'checkmate'
0-0 is castling on the king's side of the board
0-0-0 is castling on the queen's side of the board
! = good move
!! = brilliant move
? = bad move
?? = terrible move/blunder
!? = daring/unorthodox, but could be a good idea
?! = daring/unorthodox, and unlikely to pay off
1-0 = White wins
0-1 = Black wins
1/2-1/2 = draw
Sorry if you knew most of this already.
Finding out about all the different openings and theories is trickier, and you will always
encounter obscure ones you haven't heard of. If you are interested in chess, you can borrow
or buy a general chess book which will hopefully explain some common openings, and the
motivations behind them.