As I mention in the variation at move 22, there are two main things to remember at this level of playing in a handicap games. They are, in order:
a) Keep your groups alive! (Black did not lose any groups, well done.)
b) Play big moves! (See game for samples.)

For Black to build a wall facing his stones is another way of thinking big, rather than getting caught up in the heat of the battle (see game).