Hi Stephanie,
You can use SQL's OPENDATASOURCE function:
SELECT *
FROM OPENDATASOURCE('SQLOLEDB','Data Source=YourServerNameHere;User ID=DatabaseUser;Password=SomePassword').[YourDataBaseNameHere].[dbo].[YourTableNameHere]
However, this method is not the best for intensive queries. If you are planning to use this in a large query, or query that will return large amounts of data then I suggest you look at Gordon's answer and use a linked server.
Regards,
Johan