You will want to split the wood as soon as you can. Green wood splits a lot easier than dry wood.
If you stack it in rows you will want to cover just the top, a simple tarp works fine. Also, get it off the ground if you can, pallets work good for this. This way the top won't let water in and the bottom won't draw moisture up, the open sides will alow air to flow through and do the drying.
Without being covered the best way to stack is the pyramid or teepee method. Stack it up vertically, one piece on top of the next with the bark facing out. This will form a pyramid or teepee like shaped pile that will shed water down the outsides of the bark. Again, it is best if you can get it off the ground, but if you can't, moisture will draw up into the bottom pieces of the pile. Not the end of the world.
Good luck and gitter done.