The 19-year-old was given his chance in midfield at St Mary's Stadium as Ronald Koeman's men ended a run of five straight defeats with a comfortable victory.
Romelu Lukaku's own goal put Southampton ahead before Graziano Pelle and Maya Yoshida hit the target to make sure of maximum points for the hosts.
Reed was thrilled to mark his maiden start with a win that he feels will boost the belief of the side in a busy festive period of fixtures.
"It meant everything," Reed told Southampton's official website.
"That's what I've been striving for all along. I've been patient on the bench watching games and thinking about how I can influence them so I tried to implement that in my performance.
"I'm absolutely buzzing and over the moon with the win and with the boys' performance. A 3-0 win in front of our home fans was really good.
"It's absolutely massive. After a difficult few weeks where we haven't been playing badly, we've just been unlucky with a few results, to put it straight with a 3-0 win in front of the fans was really important to do.
"It's important that we know if we have suspensions and injuries that we have players that can come in and do a job. Even if we have a few losses, the team and the spirit in there stays the same. We know we can be a top four team and we're pushing to do that.
"There's belief and confidence in the changing room which stays the same and we'll go through this Christmas period with belief and character from the players which we have.
"To score three good goals, keep a clean sheet against a good Everton side with England internationals in really shows that we are a good side."
