City won 2-0 thanks to goals from Phil Foden and Jeremy Doku.
“We had good moments, many new players and the first game in this Group Stage is always important,” Guardiola said.
“We started really well then after had some problems, especially when losing simple balls. When you lose simple balls, the transition is a little bit there.
“But I saw many good things. This is the first game, we’ll prepare the next one with the new players.
“The first three points is important."
Building momentum
“We have the second one to try to arrive in the last game to have qualified then the last game to define if we’re first.
“The first step is done, this is important. We’ll recover, train good in the next few days and then have fresh legs for the next game.
“We’ll try to step by step improve things. It’s normal in this stage with new players and a lot of people coming from big injuries, step by step we’re going to take the right tempo.”
Guardiola added, “We have players in different positions, so Vitor Reis played a really good game, Nathan Ake for six or seven months not a lot without playing.
“Many players, we need to give them minutes otherwise if they come back from a long injury and don’t play they’ll never get it.
“Next game ten new players will be there to try and win the next one.”