How do you make a search function in php if you use tags separated by commas?

[Tommy Z]

I have pages which I add tags to (separated by commas) when I create them. The tags go into a mysql db row like "red,green,blue,brown,yellow". How do I add a search function that takes the tags from the db and searches my pages database using them to list pages of relevance? Such as if I search "red", i'll get all pages with the tag "red". Thank You In Advanced!