I think that the questioner is in the UK. Various American organisations do have web-based resources, but these typically include very misleading information and will only confuse a beginner. US copyright law is also rather different.

Which organisation you might usefully contact (typically MCPS or PRS in the UK) would depend largely on why you want the information. On the whole, it might be easiest all round if you said what you intend to do with the songs concerned, and tell us what they are.