then your installation is broken and imcomplete?

if you couldn't find it from clicking help > tutorials then try navigating your computer

i assume you're using windows
C:\Program Files\Autodesk\Maya2009\docs\Maya2009\en_US

where Maya2009 is the version of maya you're using

then open index.html

click learning resources (on the left frame)
click tutorials
click getting started with maya
click animation
click lesson 5: Inverse Kinematics

if you still can find it for whatever reason (like your using a mac and that address isn't going to relevant to you)
then google "maya help documentation"
it's the first link that comes up