Rosetta Stone is probably the best way to learn a new language. If you want to go to school to learn, try Queensboro Community College.
Queensborough Community College
You could also just force yourself to learn the language by ONLY speaking Spanish, having your friends who speak the language to only speak it to you. That's how I learned when I used to live in NYC and worked at a community outreach. We had a lot of Hispanic clients and I wanted to be able to communicate with them, so I just put my mind to it and had everyone speak to me only in Spanish. It was a bit difficult (muy dificil) at first but after I learned a little, it all flowed and it was pretty easy.