"You're not going to change it in one transfer window," he told the media on Monday. "We want to get the right players at the right price, players who will do their time with us, improve and make the team better."
The 53-year-old signed a four-year contract at Sunderland, replacing new England manager Sam Allardyce, who guided the club to league safety in the second half of last season, eventually finishing fourth from bottom, two points clear of relegation.
The Scot returns to England for the first time since his ill-fated spell with Manchester United and said he was eager to bring a winning mentality to the Stadium of Light.
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"You've got to remember where Sunderland have finished in the last few years, so this has now got to be a building job," Moyes told reporters in his first press conference as Sunderland boss.
"I'm here for four years and I'm aiming to bring stability."
He added: "The job is to win the games. Maybe at the start we might have to win ugly, but as we go along I want the supporters to be excited."
"I have the fourth-best winning record in the Premier League. I don't want to lose that, I want to better it. I want to win. Winning is the biggest thing for me."
Moyes said: "Sunderland have potential that many clubs don't have but we have to progress."
Sunderland are yet to sign a player in the close season, and injuries to striker Jermain Defoe, defenders Patrick van Aanholt and Jan Kirchhoff have hampered their pre-season preparations.
The club also confirmed that negotiations for former Newcastle left back Davide Santon from Italian side Inter Milan broke down last month.
However, Moyes said he expected to make additions to the squad soon.
"We have offers in for people already and we're working hard," he added.
He said he was excited to be back in England after a spell with Real Sociedad in Spain, which ended in the sack.
"I'm more excited about this challenge because of the stadium, the fans and the owner," he said.
Sunderland begin their new league campaign at Manchester City on Aug. 13.
(Reporting by Nivedita Shankar in Bengaluru,; Editing by Neville Dalton)
