Salden was a police officer the super-high gravity planet of Krypton in a distant galaxy. Although there was still a need for guards and policemen, violence, crime and war were apparently rare as Krypton was very advanced in science and philosophy. Thus the law enforcement evolved toward a low number of officers, but most of those were genetically enhanced to be huge and extremely strong. Salden wasn't, and next to his fellow officers he looked tiny and weak. He compensated by being unusually brave and working out constantly to bulk himself up.
Salden, an excellent police officer despite his human size, had a running vendetta with a villain named Gorrok, one of his world's most dangerous criminals. When Gorrok escaped from prison, he headed for Salden's home, hoping to kill the officer. The ambush was disrupted by the police before Salden could arrive and Gorrok had to flee, but he killed his enemy's wife so he'd have his revenge no matter what.
Gorrok fled toward a newly developed teleportation ship, using a newfound green element to travel to any point in the universe. He programmed it to just leave for any planet with a breathable atmosphere, but the pursuing Salden was too close. Gorrok decided to let the weaker Salden in and left immediately after, thinking he'd just kill the man while in transit.
Gorrok's tried to fight Salden and damaged the ship's guidance system, and Salden had take the controls to prevent the ship from crashing into Earth. This allowed the Gorokk to knock him out and escape, leaving him to die within the ship as it sunk beneath the Earth's oceans.
Finding himself trapped in a sinking ship under miles of seawater, Salden thought he was about to drown, but the green element that fueled the ship mixed with the water that was pouring over him, granting him the strength he needed to escape. In the following days, he wandered through Los Angeles, learned English and acquainted himself with the human culture.
Salden's main objective was to somehow get home, but for that he needed very advanced technology. Reasoning that the incredible amount of war, crime and terrorism on Earth was what was holding back technological growth, he decided to act as a super-policeman to speed progress along by removing such hindrances.
Salden, soon to be nicknamed "Superman" by the press, also went through various odds and ends to make money, such as a one-time circus performance. Lois Lane, an exceptionally greedy and talented agent, quickly sunk her teeth into him, exploiting Superman to sell stories. To keep the stories coming, Lane remained close to Superman even when that meant unreasonable danger.
When Salden had to give a name, he came up with "Clark Kent", based on a nearby poster and a street sign.
Superman soon joined the emerging Justice League of America of his reality after defeating Gorokk.
The combination of living in a high-gravity environment, along with the energizing effects of the green element give Salden amazing powers to use a Superman. He is superhumanly strong, super fast, very durable, and can see for miles in Earth's thinner atmosphere. His hi-tech flight harness allows him to fly.