Explanation

(dsname/password ...) is a required positional parameter specifying the name of the data set or list of names of data sets for which backup attributes are being changed.

For password, substitute the correct password and include the preceding slash (/). TSO does not prompt you for the password.

For password-protected non-VSAM data sets, you must supply the password that allows you to write to the data set.
For password-protected VSAM data sets, you must supply the master password of the base cluster.