Understanding Spectroscopy: Important Links...

http://www.chem.ualberta.ca/~inorglab/spectutor.htm gives basic idea about spectroscopic principles through animation . The Spectroscopy tutorial requires Macromedia Flash Plug-In (minimum version 4.0). If you have not installed it download Flash.

http://orgchem.colorado.edu/hndbksupport/irtutor/tutorial.html  is very good reference for understanding IR spectroscopy and interpretation of IR/NMR spectra. 

Other good sites for introductory IR are

http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/InfraRed/infrared.htm
http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/irspec1.htm
 

from wikipedia (http://en.wikipedia.org/wiki/Infrared_spectroscopy) you may get a basic idea about the instrumental techniques.