This is a step by step tool on how to clean and seal grout I found on home 101 blog.
How to Properly Seal Grout
how to seal grout so it doesn't get mildew-y and keeps water out. it needs to be done a 2nd time about 6 months after the first seal. wish i had known that :(
make grout look new and seal it in one step...my whole house is tile...this would make a big impact
polyblend grout renew
A very simple trick for cleaning and re-sealing your grout lines. (Works on any color grout!) http://www.askannamoseley.com/2012/04/spring-cleaning-cleaning-sealing-grout.html
How To Seal Grout | Young House Love
how to seal grout to make it easier to keep your tile clean
Grout sealers help prevent staining and protect against water damage. These products are advised for natural stone, ceramic and porcelain tile grout that are in bathrooms and kitchens. This article will tell you how to apply grout sealer....