Hi Aravinth,
OpenSAP course is focusing mainly on development perspective of SAP HANA and that too mainly on XS.
For getting HANA certified you will have to learn a lot of other things too that are not included in the course like Data Provisioning, Reporting, User Administration and Modeling in detail.
You can easily find content on these topics in SCN or visit SAP HANA Academy for video tutorials
Do study HA100 and HA300 carefully and solve all the exercises given in both these books
You can appear for certification in SAP Teched or follow steps as suggested by Prashanth above