you cant open your old Clarisworks/Appleworks with Pages, unfortunately.
However, you can use a free word processing suite to at least open and read them (but not make edits). From there you can save them into a more modern format or copy/paste the text into Pages if you wish.
LibreOffice is available here: https://www.libreoffice.org/
Install LibreOffice, and then you can launch it.
choose Open (From the File menu) and then drag your ClarisWorks file into its Open dialog. The conversion is unlikely to be perfect, but should be usable.
If you're having trouble finding the documents, you can perform a search.
In the Finder, press Command-F, click On This Mac at the top left (to make you are searching the entire Mac), then use the drop-down menu to select Kind is Other. In the text field to the right of this, type in AppleWorks. Any Clarisworks or Appleworks documents should appear.