First of all, you will need both a course section enrollment code. 

This (3E6-4A-EAE     ) is the Mathzone section enrollment code for the single Mathzone course, that I have created for my (Mr. Everest's) three Spring 2010 Math 150 : Intermediate Algebra classes

Math 150: Citrus Spring 2010 Math 150 (Intermediate Algebra)
MTuWTh Citrus Spring 2010 Math 150 (CRN #31049) Rob Everest 3E6-4A-EAE
MW Citrus Spring 2010 Math 150 (CRN #30350) Rob Everest 3E6-4A-EAE
TuTh Citrus Spring 2010 Math 150 (CRN #30352) Rob Everest 3E6-4A-EAE

Go here
http://www.citruscollege.edu/academics/courses/everest/Documents/Math%20Help/MathZoneQuickStartDocForSpring2010Math150Classes(3E6-4A-EAE).pdf
for the a Student Quick Start Guide for the above mentioned Math 150: Citrus Spring 2010 Math 150 (Intermediate Algebra)3E6-4A-EAE MathZone course to see how to register for MathZone & also how to set-up your computer for working with it.

Go here
http://highered.mcgraw-hill.com/sites/dl/free/007302872x/187232/MZ_Student_Quickstart.pdf
for the a generic Student Quick Start Guide to see how to register for MathZone & also how to set-up your computer for working with it.

Click here
http://www.mhhe.com/math/mathzone/support/ 
for MathZone support & plug-in checker (see button towards the bottom of this webpage).

 

If you bought your Miller, O'Neill & Hyde Intermediate Algebra 2nd Ed. used or through some other source than the (Citrus) Owl Bookstore, then you may not have a (required) student registration code.  This comes free with the NEW book, when ordered through the Owl bookstore.  Here is a link to a webpage :

https://highered.mcgraw-hill.com/paris/donothavecodeview.do?productid=007302872x&email=null

 that can help you to purchase a 2 year subscription to MathZone (for this book only) for a fee (I believe it is $50 presently), if you don't have one.