How to use rowClasses in a dataTable or PageBlockTable in VisualForce

Scenario:
 To have a table that would shade each alternative row.

Solution:
In your css file or even in the visualforce page place in the following:

1. In CSS:
1. .odd {
   background-color: #FCF7F7;
   }
   .even {
   background-color: #E3DCDB;
   }
2. Inside the VF Page:

So the Apex Visualforce page would look like this:
                <apex:page standardcontroller="Contact">
                <apex:form id="reportform"> <!-- Start of ReportForm-->
                <apex:dataTable value="{!queryResult}" var="r" id="ttable" border="0" rowClasses="even,odd">
                 <!--yourcode here-->
                 </apex:dataTable>
                 </apex:form>
                 </apex:page>

Now you have each other row shaded gray/white.