Sulla was born into an impoverished patrician family, but inherited wealth from a woman named Nicopolis and his stepmother, allowing him to enter the cursus honorum. During Marius' first consulship, during the Jugurthine War, he chose Sulla as quaestor. Sulla famously resolved the war by persuading a neighboring African king to kidnap Jugurtha for the Romans.
Even though there was friction between Sulla and Marius because Marius received the triumph, Sulla continued to serve under Marius. Sulla settled the rebellion among Rome's Italian allies by 87 B.C., and was then sent to settle King Mithridates of Pontus -- a commission Marius wanted. Marius persuaded the Senate to change Sulla's order. Sulla refused to obey, marching on Rome instead -- an act of civil war.
Installed in power at Rome, Sulla made Marius an outlaw and went East to deal with the king of Pontus. Meanwhile, Marius marched on Rome, began a bloodbath, got revenge with proscriptions, and handed out confiscated property to his veterans. Marius died in 86.
Cinna, as consul, passed various reforms. Sulla settled matters with Mithridates and returned to Rome where Pompey and Crassus joined him. Sulla won the Battle at the Colline Gate in 82 B.C. ending the civil war. He ordered Marius' soldiers killed. He had himself declared dictator for as long as necessary (rather than the customary six months, although the office hadn't been used for a while. In his biography of Sulla, Plutarch writes: "For Sulla had declared himself dictator, an office which had then been laid aside for the space of one hundred and twenty years."). S[u]lla then drew up his own proscription lists, rewarding his veterans and informants with confiscated land.
After Sulla had made the changes he thought necessary to the government of Rome -- to bring it back in line with the old values -- Sulla stepped down, in 79 B.C., and died a year later.