How to use the glass effect on WindowBlinds

If your computer supports hardware accelerated per-pixel alpha-blending, WB can utilize semitransparent images for window borders to give the glass effect, provided the skin has such images included. The trial version, which is what I assume you have, will support transparent borders for only the skins included with the trial - other downloaded skins will not show their transparent borders. They will work only with the paid version.

I'm using the newest one purchased under Window XP with a NVIDIA 128 MB video card. I'm not sure what the model is, but I still can't get the glass effect. I can't find anything in the option for that either. Please advice.

There is nothing in the options, the skins you download and use either have per pixel, glass or translucent window frames or not. So it is the skin that gives the glass look.
You will have to search the WB gallery here and at other sites like DA to find skins with the look you want.

Only other thing but it should not be check by default, on WB config click View my system information and make sure Never use perp pixel borders is not checked.

Open WB's Configuration dialog, select System Information. Highlight & copy the information in that window to the clipboard, then paste it in a reply post here - it should tell you whether your particular hardware supports per-pixel transparency.