querying two databases

[help_oracle]

This is SQL server query where db1 and db2 are the two different databases.
I want to execute this query in Oracle by logging into db1.

Pls help.

select C.F1, C.F2, C.F3, D.F1, D.F2, D.F3
from db1.dbo.tbl1 C, db2.dbo.tbl2 D

Thanks In Advance