Check this to give your button a shadow.

Check this to add a gradient background to your button. If you are adding an image to your button and the background color is bleeding around the edges you may want to uncheck this.

The inner gradient color will be pushed more towards a white color.
The inner gradient color is calculated more accurately based on its outer color.
The inner gradient color is inverted from the outer gradient color.
User Selected
The inner gradient color can be selected by the user. Click on the little box under the dropdown to get the color selector to popup.

Font Color
This is specified in Hex. Click on the box next to the textbox to get a color selector popup.

Once you agree to the terms of use. An image upload box will appear. You can upload an image up to 500KB in size and with dimensions up to 2000x2000.
Glass Button Generator can take advantage of PNGs with alpha channel data. This is useful if you want to upload an image with a shadow or a transparent background.
Fit Image Inside Button
This will scale the image down to fit inside of the button. Images are normally scaled to match the button size. This will scale them down a little more so the edges of the button won't be clipped by the button.
Fit Button To Image Size
This will scale the button to match the image size. The button size values are ignored. Images greater then 400x400 will still be scaled down.

Corner Size
Sets the width and height of the rounder corners for a rounded corners button. If this value greater then half of the button width or height it will atomatically be limited to half of the button size. The easiest way to create a rectanglar button that is round on the top/bottom or left/right is to set the button width or height greater then the other and then set the corner size to max.

Click this to generate your button. If your happy with the results you can right click on the button and save it.  You may need to change the extention to .png

Max button size = 400x400
Min button size = 20x20

Max uploaded image size = 500KB
Max uploaded image dimensions = 2000x2000
Uploaded image formats = PNG, JPG