Semi-transparent PNGs in Fireworks

Can anyone point me to an explanation on how to make semi-transparent cross-browser PNGs in Fireworks?

Thank you.

This similar article (http://ask.metafilter.com/24305/Help-me-learn-to-create-semitransparent-PNGs-for-use-on-the-web) may help you, as well as possibly this google search (http://www.google.com/search?complete=1&hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=fireworks+semi+transparent+png&spell=1).

Thank you