Hi again Lindsey,
I volunteered at a non-profit when I was studying in Cordoba -- Cordoba ACOGE, a pro-immigrant support/assistance group. It was the local chapter of the national organization. I had assistance finding the volunteer opportunity because my program had someone with a lot of connections with non-profits who became the volunteer coordinator, so I can't really tell you how to go about it. But, I would try to look up some non-profits (O.N.G. in Spanish -- Organizacion No Gubernamentales) and find one that interests you and contact them. For instance, I had friends who were interested in health care volunteer with an organization that did physical therapy (in water) with children....I can't remember the name of the organization off the top of my head though. Also, keep in mind though that the volunteer opportunity that they have for you may not be that glamorous. Since you're not going to be there for that long, you won't have too much time to learn/train for something that may be more involved. But, the important thing is that you'll get a chance to meet some more people and perhaps find out more about the organization.
Good luck!
Linda