Moyes enjoyed his “happiest night” at the La Liga club since taking charge in November after a Jordi Alba own goal secured victory over Barca.
“We have talked about Barcelona when I was at past clubs,” said the former Manchester United boss. “We used to watch them, like in the Champions League final, with admiration.
“We always said, ‘My goodness, how would you get a result against Barca?’ Tonight I got that opportunity.
“It is quite similar to the early days at Everton,” he said. “How to get a result against likes of Arsenal or Liverpool at that time, or Manchester United? We did not always get results, but we got some, built confidence and got better.
“We hope that will be the same here. It is slightly different in that just over a year ago [Sociedad] were in the Champions League. This year the Europa League, and now the job is to get them back there.”
Moyes hailed a heroic defensive effort from his players and urged his side to produce the same level of performance on a more consistent basis.
“It is the happiest night since I arrived in San Sebastian. We worked very hard. The players showed courage and defended incredibly,” added the Scot.
“This team has shown it is capable in the big games against the best teams in the league and now we must show the same capability to win the other games. At home, for example, we have??let a lot of points slip away.
“We defended well tonight and that is what we have to do in all the games, but in other games when we don’t have to defend so much we also have to pass the ball and attack better.”
Barca boss Luis Enrique paid a heavy price for leaving both Lionel Messi and Neymar amongst nearly 300 million euros of talent on the bench.
Both South American stars only arrived back in Spain on Friday after an extended Christmas break and Moyes defended his counterpart’s decision to only introduce them after the break.
“The best players can’t always play at their best level in every match,” he added. “The biggest games for Barcelona are still to come and in that sense I think Luis Enrique made the right decision.
“I was hoping this would happen, that some of their most important players wouldn’t start and we were prepared for that.”