added field info

README.md

@@ -158,11 +158,14 @@ All language identification provided by Twitter API.
 
 ### Data Instances
 
-[More Information Needed]
+Data is provided in gzip'd files organized by year and month of tweet origin. 
+Tweets are one per line, with fields separated by tabs.
 
 ### Data Fields
 
-[More Information Needed]
+* `tweet ID`: ID of tweet
+* `lang`: ISO 639 code of language, provided by Twitter metadata. Accuracy of label is not known.
+* `year`: Year tweet was created. Year is also provided in the file names.
 
 ### Data Splits