If you are using Microsoft Works 2.0, ClarisWorks (2.0 and 3.0) can read the database in directly. With ClarisWorks launched, select OPEN from the FILE menu, click on Database as the type of document, and then double click the MSWorks DB file. The file will open into a ClarisWorks database. Save it, and use it.
If you are using Microsoft Works 3.0, you must first save your database as a DIF file (this saves the data in a text format, with the field names), under a new name (ie., if file is called "My Database", then you would rename it something like "Import this to ClarisWorks"). Then, with ClarisWorks launched, select OPEN, click Database, and then double click the DIF file ("Import this to ClarisWorks"). The file will open into a ClarisWorks database. Save it, and use it.