You could use the MSSQL server built in
MONTH Function.
Something like this should work:
SELECT * FROM TableName WHERE MONTH(CreatedDate) = 10;
or if you want to query based on year and month:
SELECT * FROM TableName WHERE YEAR(CreatedDate) = 2013 AND MONTH(CreatedDate) = 10;
... hope it helps.
[EDIT]
To query by specifying a month name, (which is not as an efficient solution compared with querying by month number), have a look at the MSSQL server built in
DATENAME Function.
Something like this should get you started:
SELECT * FROM TableName WHERE DATENAME(month, CreatedDate) = 'october';