[REBOL] How can I process a whole directory

[Tiana . Zhang]

Hello, I have a rebol script process a specific file. How can I add code to make
it process all the files in the directory?

I tried to change the following line
    FileStream: read/lines %files1.txt
to
    FileStream: read/lines %mydir/*.txt

But it didn't work. 

Any quick fix for this script?

Thanks

tZ