Use only for module names, not for full file names. If your file classes.chpldoes not have an explicit module covering all its contents, enter
use classes;
to access its contents from another file.
If it classes.chplis in the same directory as the file with the use statement, this should be all that is needed to access its characters.
classes.chpl , -M --module-dir. , usesClasses.chpl classes.chpl, classes.chpl helpers,
chpl -M helpers/ usesClasses.chpl