You may get more reliable answers in a Works group, but I think the
situation is as follows:
a. The Word processor in the last few versions of the Works /Suite/ is a
version of Word.
b. the native Works (not the Works Suite word processor) word processor
uses .wpd format
c. you won't be able to use Word Automation from C# without Word
d. although technically speaking you /might/ be able to use Word's Export
converter for Works without Word being present, as far as I know you break
the license conditions if you install or use the converters without
installing Word. It's a non-trivial exercise technically and I suspect from
C# it would be even more difficult.
e. I do not think there is an equivalent way to Automate Works to generate
a .wpd document.
f. I do not think the .wpd format is published, so I do not think you can
generate it directly from code. It looks "binary" to me.

Which means that the only way you are likely to be able to do this is to
modify your C# program to generate .rtf or .htm format directly, assuming
Works WP can open either of those formats. Producing .rtf is non-trivial
unless you are always writing documents with the same layout and different
contents. In that case, you should create the document layout you want in
Works, save it as .rtf (if possible), then use that as the besis for
generating your own documents. Producing .htm format is probably simpler,
but there is usually no way to insert features such as eaders and footers,
and so on.