How to link Oracle server from SQL server 7.0

My app was build with Delphi5 and SQL Server 7.0.
I've added Oracle from SQL Server 7.0 as follow:

EXEC sp_addlinkedserver
    @server = 'OracleServer',
    @srvproduct = 'Oracle',
    @provider = 'MSDAORA',
    @datasrc = 'MyData'

But I don't know how to create view or add linked tables to
retrieve data from tables of Oracle database. Furthermore,
I don't know how to pass Username & Password parameters
to connect to Oracle server added.

Any help greatly appriciated.