I'm at the part where i need to shoot arrow to open door, but can't figure out how to move the walls. can anyone help please?

This post contains solutions and therefore this thread should probably be in another forum- the one for cheats and solutions. but what the hay-

KIll all the bad things you can see in the room to get them out of the way. There's a door along the side wall that goes to another area- go there. Keep killing bad things. Keep going into open passages and doors until you find the final switch. Once this is activated the doors will open in the arrow room and you'll kill more bad things and then have time to shoot the arrow at the target. You have to aim a little high.Save the game before shooting arrow.

If you miss the shot you can go retrieve the arrow, I had too twice.

Also as I found out its entirely possible to do without killing anything, just really hard lol.

You mean you stood there while zombies and what not tried to get at you? Man.

Yeah I had run out of arrows before getting to the statue room, and Cheza is very very poor with a blade. She has a great dagger but its enchantment wore off, then it broke lol. So I avoided the two zombies in there. Had to sneak/run through the other area to the switch, couldn't kill anything. Then in the statue room I lured the zombies and extra spawned skeletons to a corner then used my speed and acrobatics to get to the platform and fire the arrow. Missing the first two shots due to zombies hitting me complicated matters lol.

That's what I love about Oblivion- the things that happen you can't predict- game after game.

I had this; the walls won't go down so that you access to the platform. If you're on PC, use the console and enter

tcl

It will allow your character to "fly" to the platform. When you're there, re-open the console and enter tcl again.