Place wedding video on track one and move your scrubber to the point that you would like to take a snapshot.
In the preview area, there is a camera icon. Press that and a still photo of your video at that frame will be added to your media room.
Take that still photo and put it on track two at the exact spot you created the still from. In order to get this in the exact spot, I would take and split your video (in the first step above) at the spot you took your snapshot. Set the duration you would like the snapshot to be displayed for.
Then click the modify button to resize it at its starting point, add motion to it using the motion tab or use key frames to create custom motion. Also go to the end duration and resize it again to create the shrinking effect you are after.
As for the sound effect and flash, you should be able to find the click effect in a .wav on the web. The flash effect I'm not too sure on where to get it but someone here will point you in the right direction
I've simplified the directions here somewhat. It will take some learning on your end but that learning will pay dividends down the road.
Hope it helps some.