Check out this animation. It will explain it to you.
Most popular audiophile solutions are: (alphabetically)
Auric Illuminator - CD/DVD Cleaner
Disc Doctor CD Cleaning System
Shine Ola (Record Research)
Vivid (Walker Audio)
Inexpensive cleaner that provide good results: (alphabetically)
ROR (residual oil remover) V-Vax Corp., Chicago
Novus Plastic Polish #1, Novus Inc. Minnesota
3M Plastic Polish, 3M Corp.
Search Audiogon posts for reviews of the audiophile solutions. For the inexpensive versions, buy and try.
There is a great post about CD's and long term damage that can occur by using the wrong types of products on them. (Remember the Armor All disaster? I do, it ruined around 500 of my shiny discs).
Here's the link: http://forum.audiogon.com/cgi-bin/fr.pl?ddgtl&1096407732&read&keyw&zzshine=ola
I hope that this helps ...