But now to proceed with the actual game:--

6. K's Knight to K's B's 3d. 6. Queen to K's B's 3d.

Bringing out the Knight is good play; you not only threaten to win his
Bishop, but you afford yourself an opportunity of castling whenever it
may be needful. Black would have played better in retiring the Bishop
from the attack to Queen's Knight 3d square than in supporting it with
the Queen.

7. Knight takes Bishop. 7. Queen takes Knight.

Both parties played well in their last moves. You rightly took off the
Bishop, because supported by the Queen he menaced your Queen's Kt's
Pawn, and Black properly retook with his Queen instead of the Knight,
because having a Pawn ahead, it was his interest to exchange off the
Queens.

8. Q's Knight to Q's 2d. 8. K's Knight to B's 3d.

You played correctly here in not exchanging Queens, and also in
protecting your Bishop and your King's Pawn, both of which were attacked
by the adverse Queen; but all this might have been done without impeding
the movements of any of your Pieces, by simply playing Queen to King's
2d sq.; as it is, the Knight entirely shuts your Queen's Bishop from the
field. Black properly brings another Piece to the attack of your King's
Pawn:--

9. K. B's Pawn to B's 3d. 9. Q's Knight to King's 4th.