Use this query:
RESTORE DATABASE [SouthWind]
FROM DISK = 'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\South.BAK'
WITH REPLACE,
MOVE 'SouthWind_Data' TO 'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\SouthWind_Data.MDF',
MOVE 'SouthWind_Log' TO 'C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data\SouthWind_Log.LDF'
where FromDisk is where the .bak file is kept on Server B and MOVE specifies the location of the data and log file.