Chelsea won 2-0 via goals from Enzo Fernandez and Pedro Neto.
"The most important thing was to get the win and that’s what we have done," Colwill told the club's website.
"We picked and chose our moments where we could attack and where we could keep the ball. It wasn’t the perfect performance, but in tournament football, you just need to win.
"We’re coming up against different teams and that will be a huge challenge, but we’re going to enjoy it and learn different things. The tournament has kicked off, and our focus is on the next game now."
England defender Colwill also said: "To take a clean sheet is the most important thing for the defenders.
"You know we’ve got amazing attackers and they always score goals. So for us defenders in the team, we need to keep clean sheets to win games. And of course they had their chances, but hopefully next game we can minimise them."