transparent gif in ps 6.0

I know this sounds a bit amateurely..but how do you make a green square transparent, so the green is transparent..in ps 5.0 I know how to do it, but not in ps 6.0..

anybody can give me a hand

CyberoX

Creating transparency with Photoshop 6's Save For Web

Finally you can easily save Web graphics with a transparent
background. Just keep your image on a layer with a transparent
background. Delete the actual Background layer from the Layers
palette and then choose File > Save For Web. Then select the
Transparency check box and click OK. Your Web graphic will
automatically be made transparent on the Web. Keep in mind that
this works only on GIF files. If you save the graphic as a JPEG
select Other from the Matte pop-up menu. Then specify the color
of the background of your Web page so the graphic blends in.


-Element K Journals' Inside Photoshop