Creating a linked Server on SQL Server

EXEC sp_addlinkedserver @server='GM', @srvproduct='',
@provider='SQLOLEDB', @datasrc='databaseIP,Port',
@catalog ='DBName'
EXEC sp_addlinkedsrvlogin 'GM', 'false', NULL, 'DBUser', 'DBPassword'

--The Query, Using the Server Database you are already in and your new linked server: GM--
SELECT
NUMBER,
DT_CREATED AS DATE_CREATED,
PRIORITY,
(SELECT COMPANY FROM GM.myDatabase.dbo.myTable WHERE ACCOUNTNO IN (SELECT TOP 1 ACCOUNTNO FROM GM.myDatabase.dbo.myTable WHERE Field1=(SELECT CUSTOMER_NUMBER FROM CUSTOMERS WHERE ID=ID_CUSTOMER))) AS COMPANY FROM MAIN_TABLE