Annotated Chess Guide: Part of the Beginner's Chess Guide (Section 1)
In the Algebraic system, CAPITAL LETTERS are given to represent each of the major pieces on the board - be they Black or White:
N = kNight
B = Bishop
R = Rook
Q = Queen
K = King
So, at the start of the game, here's the position of the major pieces, using Algebraic notation:
White has kNights on: b1 & g1
Black has kNights on: b8 & g8
White has Bishops on: c1 & f1
Black has Bishops on: c8 & c8
White has Rooks on: a1 & h1
Black has Rooks on: a8 & h8
White has his Queen on: d1
Black has his Queen on: d8
White has his King on: e1
Black has his King on: e8
Note: There is no letter-replacement for the Pawn. Why they don't simply have a lower-case 'p' ... who knows? But, they don't.
Suffice to say, at the start of the game, here's the position of the Pawns, using Algebraic notation:
White has Pawns on squares: a2 to g2
Black has Pawns on squares: a7 & g7
So, "how do you know when a Pawn moves?" Glad you asked, as it's mentioned next ...
Moving On: Recording Moves (Page 6).