Lucky you, Encore comes with a handful of glass layer styles–they’re right there in a folder called “Styles.” I imagine you can use them in Encore somehow to make buttons, but they are all saved as .psd so maybe PS is their intended platform.
Just open a style in photoshop. What you will see is a document that is
a–too small
b–only has a tiny square in the middle, however the square will look really cool. (Well fairly cool. These are not groundbreaking styles.)
You need to get that layer into a bigger document and either use the drawing tools or shape tools to make some rectangles–(anything you paint on the style layer will also have those styles) or copy the styles to some other rectangles you already have somewhere.
To make highlights, add some adjustment layers–hue/lum/sat and levels. Then you can turn them on and off and save off as pngs for use in encore.
There are also tons of tutorials for glass buttons on the web. The easiest will be ones those created entirely with layer styles. some will even have the styles themselves available for download.