saving a partially transparent image in Photoshop, how to make it work?! Options

[souldreamers]

I'm going crazy! Anyway, I'm working on a new xanga skin and I'm trying to make a part of the image partially transparent so you can see some of the background through it. But everytime I save it, the transparency doesn't show! The weird thing is that it'll show up in the Photoshop window but after I save it, the partially transparent aspect of it is gone, only the completely transparent part of it works. I've never tried this before so I don't really know how to do it. Here's the image so you get an idea of what I'm taking about: http://www.xanga.com/home.aspx?user=trendygirlv13 It's a work in progress. The purple stripes is what I wanted semi-transparent.. so you can see the background. I did set it to like 70% opacity and you can see the transparency in Photoshop... but it just won't show up after I save it! I don't get it.. cuz the transparency worked for the area around the girl/flower.