How is this a blunder

Apparently Castling was brilliant

why is this brilliant?

Was going to take the rook, but I was proud to find an even better move.

bro

Why is A6 better than A5 in this position? Only thing I can think of is because my pawns are no longer connected

If this doesn't hurt the eyes I don't know what will.

Why was taking their rook better than moving my queen out of danger?

When your opening prep works beautifully.

my first fork is also a checkmate- my 2nd game against a real player

Fast checmate