What is different bettween Cassandra NoSQL data model and SQL data model can any one tell. cassandra data model and sql data model 
how we can define row and column with cassandra data model?
Cassandra is a Columnar Store NoSQL Database, Which goes beyond the Key Value pairs.

A Column family in cassandra is a container for rows, like table in any RDBMS.

And These are Stored and represented in Json Formats.

Below are some links where you can get more info:

http://wiki.apache.org/cassandra/DataModel

http://www.datastax.com/docs/0.8/ddl/index

http://www.javageneration.com/?p=70