Here are a few tips to help you use WordPad:
To open and save files, select File, then select New to create a new document, Open to work with an existing document, or Save to save your document. (If your document doesn't have a name, WordPad will ask you to provide one.)
To learn how to set a document type to open a different app, see Change default programs in Windows 10.
If you need additional help, ask the Microsoft Community.