|First, you need to clarify how this header is composed. Second, you need to specify what is intended by "a designated portion" of the file's name. The former has infinite possibilities, the latter effectively so. Some examples would be really really good. |
(For #2, we could just append a "1" to the filename but keep the CSV extension, for example.)
Basically, create the new-file-name, echo the header to the new-file-name, then copy new-file-name + original-file-name.