You had seen many Glossy buttons in many websites. Here is a simple way to make a round glossy button.

Step 1. Open a new photoshop document with size: 200*200 pixels and background transparent.

Step 2. Select the elliptical marquee. Draw a circle with required size.

Step 3. Fill the circle using required color. Here Blue is used.

Step 3. Create a new layer. Using the elliptical marqee tool, make an ellipse as shown.

Step 4. Take the gradient tool. Apply gradient from bottom to top with white color having transition from opacity 0% to 100%. Do this as shown.

Step 5. Deselect.

Step 6. Select the first layer. Add some layer styles: Drop shadow and inner shadow as shown.

Step 7. Your button is ready. Save as GIF or PNG for using it in your website.

You can add pictures or your logo inside the button.