To start tagging:
Go to the tagging page. You'll be prompted to create an account or login first
List every word you can think of when you see an image. There are no wrong answers. Separate each tag with a comma and then hit 'save'.
Note: Don't worry about listing both the singular and plural versions of a word (ex. 'dog' and 'dogs'), we generate those on our end.
There are a lot of photos to tag, so take a break and don't feel like you have to tag every photo. A few photos tagged well is better than hundreds tagged badly.