Need to convert csv to flatfile

Hi team,

I am quite new to webMethods development.I have a task of converting a csv file to flatfile(removing the header and trailer from csv)
Attaching the sample docs here.
I have written a service it runs fineo but I am stuck up after converting to string list.
Please let me know how to send the ff to outside webMethods.
Like for now I have used convert to string and made a string list.
I am stuck up with the string list.

bookingsff.txt (329 Bytes)
bookingscsv.txt (225 Bytes)

Hope this helps.