A) You would have to incorporate that gene into the bacteria's plasmid (genetic information that isn't in its main genome) so that it can use it and express its message. This is done using enzymes that cut that circular plasmid, insert the gene you want, and put the circular molecule back together. Once you have the bacteria with the plasmid in it, you replicate that bacteria, so all the resulting copies will have that gene and they'll express it.
B) If not enough protein is being produced it could be because you don't have enough bacteria, you'd need a bigger population. The medium the bacteria is in also should be optimal so that it can be as efficient as possible.
