Sean Marks sat facing a room of bright cameras and outstretched tape recorders — standing room only, Friday night — and calmly confronted this Rubik’s Cube of a conundrum.

How do you improve a 15-40 team that doesn’t own its own natural draft picks for the next three years? How do you do anything positive with these final 27 games of the season? How do you find a coach, establish a winning culture and make Brooklyn excited about its beautiful arena, its trendy jerseys, and it’s woefully underperforming team?

How do you do it soon?

Measured, but not overly cautious, the Nets new general manager began clicking his colors into place — laying the early blocks of a plan that, at the very least, proved the team hadn’t been twiddling its thumbs during its two-month search for new management. The search was shortlisted to eight people, said Dmitry Razumov, chairman of the Nets’ board of directors, and Marks was chosen by unanimous decision.

Citing league sources, ESPN reported that Marks signed a four-year contract for more than $9 million.

“I think you look for players that are going to fit within your culture,” said Marks, who served as the Spurs assistant GM for two seasons. “Whoever we bring in here, they are going to play team basketball, they are going to be competitive on the floor. The coach is going to have a defensive mind-set.”

The puzzle is still in its very early stages, but Friday night, Marks made it clear that there are at least a few things he and owner Mikhail Prokhorov had settled on. The entire staff organization will be expanded, he said, including the scouting department. Marks plans to bring in some of his own personnel and he’ll be making hires in the next two to four months, he said, hoping to establish a sense of culture in the organization, similar to the one that has carried the Spurs, with whom he won two championships, as a player and as an assistant coach.

“It was a difficult decision” to leave the Spurs, he said. “And to be honest, it’s time for me to see if I can do this.”

The search for a new coach will be driven by Marks, Razumov said, but both said it would be “a process” — something that most likely precludes a decision this season. The search will be “worldwide,” Marks said.

The roster will be evaluated immediately, said Marks, who stressed this was “not a wasted year.”

“I have a clear vision of what I’d like to implement,” he said. “It’ll be built through a solid, strong foundation, a systematic process,” adding that Prokhorov’s investments — the training facility, the D-league affiliate — “tell me he is willing to spend the money in the right places.”

A strong presence in the free-agent market this offseason will be necessary, despite good young talent in Rondae Hollis-Jefferson and, to a more unproven degree, Markel Brown and Chris McCullough. Marks won’t stop there.

“You can commit to free agency,” he said. “ you’re building through the European market, you’re building with your D-League . . . Not having a draft pick as we stand right now, but that too can change.

“We will find the best fit for Brooklyn and we will bring them here.”

The Nets hope that by hiring Marks, they’ve already started the process. Count that as one cube clicked into place.

Notes & quotes: Tony Brown fully understands that his days as head coach might be numbered but it hardly means his career is over. “It’s not just an audition for Sean,” he said. “A lot of teams are looking to see how I’m doing in this position, so it’s a resume-type deal here that I can run a team and run it successfully . . . If I can improve the way they play over this period of time of the season, I think that will be a plus and a feather in my cap.”