Is c++ soley used on and corresponding to Windows? I've heard Java Script is universal but sometimes sluggish and not always the best choice. Is this true? And can you tell me a little bit more about PHP and MySQL's specialties?

Basically, I'm really looking for languages that will be most effective in manuevering around database security systems and small organization websites. I'd like to gather some hidden information from an article based page. But in essence, an easy to learn first language to break the water for me would be a good start.