How do i download image files ? - MIME HEADERS HOW TO USE ??

I am trying to download a file using HTTP. Text files and HTML files are getting downloaded perfectly, but not any other files.
I refered Complete Reference Java 2, I found that MIME Header has something to do with this, but was not clear.
I tried downloading the file in byte array and then write it but this does not work at all.
So can any 1 help me in this regard.
Thanx in advance,
Tejas