Creating a Month Name in the Date Dimesion

HI,

I know the question is very fundamental. But I am new to the WEBI . So here is my question. I want to display the Month Name to the user , which they can use in filter . But the query should pass the date.

here are the dimensions I created

Month Name ==> to_char(transaction_date,'Month')

Year ==> to_number(to_char(transaction.transaction_date,'Month'))

but when in WEBI the field is put into the where clause, it causes the resulting sql statement as

select name, sum(sales)

from customer , transaction

where customer.customer_id  = transaction.customer_id

and to_char(transaction.transaction_date,'Month') between 'January' and 'December'

and to_number(to_char(transaction.transaction_date,'Month')) = 2013

what I want the SQL to be is 

select name, sum(sales)

from customer , transaction

where customer.customer_id  = transaction.customer_id

and transaction.transaction_date between to_date('01-January-2013','dd-month-yyyy') and to_date('01-December-2013','dd-month-yyyy')

The idea is to display the user only the month and year  and the query apply the where clause within those two boundaries .

All suggestions are appreciated.

Thanks