No Colours ?? Try this before your IDL commands

device,decomposed=0

You may find that the IDL graphics window does
not refresh if it is obscured by another or has
to be redrawn for some other reason. You can 
correct this by setting.

window,(index # if not 0),retain=2

Mapping an image to the Globe with IDL

image=bytscl(data)
map_set,<<..settings..>>
img=map_image(image,startx,starty(,lonmin=..,lonmax=..),/bilin)
tv,img,startx,starty
(to overlay a contour plot) contour,data,<<..settings..>>,/overplot
(overlay grid) map_grid(,color=0)
(and continents) map_continents(,color=0)

Producing Postscript Output with IDL

set_plot,'ps'
device,xsize=#,ysize=#,/inches,bits_per_pixel=8,/color
<<plotting instructions>>
device,/close
spawn,'mv idl.ps filename.ps'

(to return to standard plotting mode) set_plot,'x'

Reading a File into IDL

(define a string variable)var=''
(prompt for input)read,var,promp='Enter Filename:  '
(open logical unit to read in data)openr,1,var