The 49-year-old Portuguese was confirmed as Stuart Gray’s successor at the end of last month but was formally introduced to the media by the club’s Thailand-based chairman Dejphon Chansiri.
Carvalhal has had previous spells as head coach at a host of Portuguese clubs, including Sporting Lisbon, and has also had a brief spell in charge of Turkish club Besiktas.
“Next season we must understand the process that we must change something,” Carvalhal said.
“For the last 15 years the club has not had success and we must accept that. They’ve not been good years for Sheffield Wednesday.
“So it’s time to try and change that. It’s time to give a new era to the club.
“The first step when you have a new coach is to bring new ideas. Different coaches play different ways and we will play different.
“These things take time, but we’re taking the right steps and we’re very happy with the players.
“We’re feeling the enthusiasm of the massive (fans). We want to push them because if you push them with good football they will push us to win. This is something we must create.”
When asked about challenging for promotion next season, Carvalhal added: “I think we are outsiders.
“We have to create a strong team and we will do that. I have spoken to the players as I have spoken to the chairman and the first step is to get our massive fans behind us, playing good football.
“We must get the fans to enjoy what we are doing and also we must enjoy what we are proposing to do – this is our first step.”
Carvalhal has been followed to Hillsborough by Joao Mario, Joao Cunha and Bruno Lage, who make up his coaching staff.
Tuna magnate Chansiri, who completed his takeover in January and sacked Gray on June 11, has made wholesale changes to the club’s management structure since the end of last season.
Former West Ham and Newcastle manager Glenn Roeder, ex-Fulham coach Jonathan Hill and Paul Senior have formed a sporting director committee to act as Chansiri’s advisors.