dude to be honest if you havent taken out a leading edge before i wouldnt attempt now :) you can quite easily burst your bladder if you get a knot in it and pump it up to much, plus its just frustration to the max unless you know what your doing. My suggestion is take it to the store you bought it from, they are generally willing to help. watch them for the first time then you can do it yourself.
but in saying that, to be honest i dont think you need to take the bladder out to get rid of excess water. Its happened to me on more than one occasion and i have fixed on the beach simply by grabbing a mate we hold one end up each and face the deflate valve towards the ground the just roll the kite up and just make sure you squeeze all the water out of it.
But also in saying that if you having trouble putting the bladder you have already taken out then you should take it back to the shop and get them to show you how to put it back in because dont incorrectly you also risk bursting your le bladder.
Hope this helps mate

ben