The Colombian - signed from Hertha Berlin during the close-season - came off the bench to score twice as Dortmund won 3-0 at Anderlecht in Group D on Wednesday.
Despite featuring in five of Dortmund's six Bundesliga fixtures so far this season, Ramos is far from a guaranteed starter having come off the bench in two of those matches.
But the 28-year-old declared his delight at getting off the mark in the Champions League.
"Obviously I'm over the moon," he told the Bundesliga's official website. "For one thing because of the win and for another because of my two goals. I hope it continues like this for us and for me.
"It's a really special moment when you score in the competition for the first time.
"I've always dreamt of scoring in the Champions League. It gives me the belief going forward."
Ramos now wants his stellar display to help him tie down a place in Jurgen Klopp's starting XI.
"It goes without saying I'd love to start every game, but there are so many quality players at Dortmund from front to back.
"In that respect, it's essential to be on top of your game when the chance comes."
Dortmund face Hamburg in the Bundesliga on Saturday.
