Transparent foreground

I'm just wondering if there is a way to make something in the foreground so that you can see the background whatever it may be.

How I tried to do this was created a file with a transparent background and then added a new layer with 30% opacity and then typed the text I wanted you to be able to see through, but when I save it as a png it just makes the background white and as a gif it makes the entire image transparent so the text doesn't show up at all.

Thanks for your time,
H²

png-8 and gif.... you must check transparency AND choose a transparency DITHER (pattern dither most likley)

png-24 just make sure Transparency is checked