Do you want to meet some rollerbladers?
The best place to go is the Palau de la Musica square, placed in the old bed river. Most people like to skate there because it's a really good place to start obtaining your skating skills.
Also experimented skaters meet there on Thursdays at 23.00h to make a tour around the city
What are you waiting for? Grab your skates and come! New people is always welcome!