The region of the graph that is first order in substrate concentration is at the base of the rectangular hyperbola where the slope is steep. Here the rate is proportional to substrate concentration. At the top of the graph where slope is zero, the graph is zero order in substrate concentration. You looked at zero and first order reactions in chemistry. Once again you need to use the rate vs substrate concentration graph on p.68.
V is the maximum velocity of the reaction, shown at high substrate concentration.
K m is the Michaelis constant and is the concentration of the substrate giving half the maximum velocity. Whatever molecule you choose, it must have a hydrocarbon chain a few units long followed by a group with a positive charge. The two negative charges would repel one another so that glutamic acid would never be positioned correctly for trypsin to cleave the peptide bond to the right of it. The new enzyme might recognise acidic residues such as glutamic acid. Competitive inhibition is where a molecule resembling the substrate binds to the active site of the enzyme.