First, let's start by adding a layer at the top. Call this "Canvas" and the bottom layer "Game". I recommend keeping the gridsize at 32x32 and setting 'snap to grid' enabled. Now stretch the canvas object to half of the viewport and position it in the top-right corner. Move it to layer "canvas" and lock the layer. Everything else will go on layer "game". Add the background object, stretch it to the whole layout, and lock it. Add some solids around the edges about 8 blocks thick and about 18 blocks thick on the right side. This is important to do because you must always have both players in the middle of their screen at all times. Add a few more solid objects of varying sizes around the layout for the players to jump onto. Finally add the players. The layout should look like this: