creating and rebuilding index with oracle table

Hi

What is the best way to create and rebuild index with SAP -Oracle table ? I do understand that I can create index with SQL, with brspace and with SE11, but want to use the best method. Also want to know if there is any risk involved with online rebuilding of index. if there is any third party tool available for rebuilding index online without affecting the performance of the system

Any feedback will be appreciated

Al Mamun