I'm not familiar with that version so things might be in different paletes but there are two ways you can do this.
1. first you need to, if possible on your version, make a white shape and use the layer features to add some form of shading (and contour if you want a glassy looking shape) then turn down the master fill opacity on the shape to 0% but set the shading effects at around 45%-60%(depending on how transparent) in order for this to work the shading must be done as a layer feature and not just painted on so that it stays seperate from the fill color(white).
2. or make a selection that is the shape you want then using the airbrush tool at 10%-25% opacity(or low opacity paint brush if that tool is not present) and use that to lightly shade the edges of the selection to give the shape form.
let me know if this helps, sorry if not all of these features are available in your version if you do this stuff alot I would recomend getting at least photoshop 5 which should be pretty cheep now, but the most recent the version the better.