how do i edit mime types

[Joe Briggs <joebri freewwweb com>]

how do i edit mime types to NOT open separate instances of compupuic
when
dl'ing jpgs?  for the jpeg/jpg file type, it's currently set at
<compupic %f>.
 removing the <%> or the <%f> renders it inoperable.  i want it to load
one
image, then load the *second* image, without multiple instances of a
running
program. 

thanks!