To encode a binary file named foo
uuencode foo /dev/stdout > fooencoded
You will see only ASCII text. The textfile will be larger than the original binary.
This is normal behaviour.
To decode the file:
uudecode fooencoded > foo.bin
foo.bin should be the original binary file. So try
diff foo foo.bin
The result should be nothing as the files are the same.
So, encode your binary file to ASCII that is postable, post that ASCII file (copy & paste, or whatever you need to do with your "post to a newsgroup") with instructions as to how to decode it.
Please seeman uuencode