"I will work in the same way as I did in Porto, or even better if possible because I want to give my all to my dream," Anderson told the website of Gestifute, his agent's company.
"I acknowledge my value and I just hope everything goes well. I am prepared for everything. I am so motivated."
Cazrlos Queiroz sees Anderson and Nani as signings for United's future.
"It is a significant investment in Manchester United's prospects for the next 10 years," He told TVI television channel.
"It's worth imagining a forward line with Rooney, Ronaldo, Anderson and Nani, these are players with enormous creativity.
"It's an attraction being able to develop their abilities. I have worked with young players many times and their potential is impressive.
"These signings mean the end of a long observation process. They are players who correspond to the club's intentions. They are young and have plenty of potential and talent."