You can consult a full example of schema for multiblog here:

http://arin.me/blog/wtf-is-a-supercolumn-cassandra-data-model

In fact, Cassandra is not RDBMS so you'll have to create a CF for everything you want to "index" as Jonathan's suggestion.

On Tue, Feb 2, 2010 at 10:27 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
You would add a columnfamily with a row per month and write blog posts
(either ids or entire post data) to that CF.

On Mon, Feb 1, 2010 at 9:10 PM, Rockett Williams
<rockett.williams@gmail.com> wrote:
> Most people are aware of Evan Weaver's (from Twitter) blog post introducing
> Cassandra.
> http://blog.evanweaver.com/articles/2009/07/06/up-and-running-with-cassandra/
> In the post he uses a example multiblog application -> a blog for multiple
> users.
> I was wondering how would you be able to query by date for the example which
> would be a common scenario.
> For example, I want all blog posts from the month of January.
> What schema changes would be required and how would you approach the problem
> using the API.