Depending on what version of Word you have the instructions below may differ. If in doubt search F1 Help in Word for "data source". The following instructions apply to Office Word 2003.
1. Select Tools | Letters and Mailings | Mail Merge | Select List.
2. Click on Browse and the Select Data Source selection box should appear.
3. Choose '+Connect to SQL Server database' or click on the New Source button, then Microsoft SQL server.
4. Enter your server Name: (local) if you are on RMS database server or enter the name of the server where the RMS database resides.
5. Select SQL Authentification and enter your username (usually sa for RMS) and database password (the same username and password you use for Store Operations Administrator).
6. Select the database you'd like to connect to from the drop down list, then PUBLIC_Customer and click Next.
Enter a description so you'll know what connecion means next time. :-)
7. Click Finish and wait for the database connection to load.
Make your selections and complete the Mail Merge routine you wish to run (form letter, mailing labels, email broadcast, etc).
Refer to Word's F1 Help if you need further instructions.