In the following link of Economic Times, there is brief description of Wholesale Price Index and Consumer Price Index. There is a brief explanation on their respective significance. The new base year which is going to come into force in 2010 is also discussed. It explains that how many goods/companies are included calculating the ratio of WPI.
For non-economic candidates, it is a good write up. Keep a note of it.
For Consumer Price Index (CPI) check HERE. It is more elaborate with US economy as it is pivotal economy. However, it can be skipped if not comprehensive as WPI is the basis of declaring the inflation for which Economic Times is giving this Lesson on Basics.The CPI is also used as such but as per ET, WPI is the basis in India. (Student with Economics background is requested to comment if the blogger is wrong. The blogger will be highly obliged.)