Hello, I am planning to take the certification in DB2 DBA on OS2.. Could any one help me about what tests I should take in what sequence? Also please let me know where can I get the material or books and how much are the fees structure? thanks in advance.

I assume you mean z/OS. All that information is available on the IBM website. IBM relies on 3rd party testing companies to administer the exams, and the IBM website provides information for contacting the company who does that depending on where you live so you can get information on the cost of each exam.