Add Linked Server Failed

hi,
i have added a link server but it fails when i try to retrieve data.

SQL server in on the same machine
i have created the another SQL server instance

Main Server: SERVER1
Instance: SERVER1/NewServer

EXEC sp_addlinkedserver @.server = SERVER1/NewServer, @.srvproduct = 'SQL Server'
EXEC sp_addlinkedsrvlogin 'SERVER1/NewServer', false, NULL, 'sa', 'test'

select * from SERVER1/NewServer.db1.dbo.tbl_Prouduct

when i try to run the above query it gives me the error
Server: Msg 170, Level 15, State 1, Line 1
Line 1: Incorrect syntax near '/'.

anyone have suggestion??
Aditry this
select * from [SERVER1/NewServer].db1.dbo.tbl_Prouduct|||i try this too but its still not working