Select the large, visible shape and go to the Appearance panel. Open the fly-out menu and click on Add New Fill. This will add a second fill for your shape. Select it and use the linear gradient shown in the following image. The yellow zero from the gradient image stands for Opacity percentage. This means that you need to select the gradient slider and lower its opacity to 0%. Next, add a simple stroke for your shape and select it from the Appearance panel. Make it 5pt wide, align it to inside, set its color at R=255 G=255 B=255 and lower its opacity to 5%. Finally, reselect the entire path and go tot Effect > Stylize > Inner Glow. Enter the data shown below and click OK.