I removed the blue text from your post. As EtphTheElephant already said, that is reserved for mod use only. Please read the forum rules, linked at the bottom right of every single page - you've made 4 posts and you've already broken them 3 times.
Do a search on the forums for shift click mapping. There are a number of threads that explain, in detail, how to do it.
To be honest, I don't like the way Ace does its autotiles - it tries to be clever and anticipate what you want to do, but most of the time it ends up just messing things up, making you spend even more time fixing it and doing it properly. I much prefer XP's mapping system.
Draw your water where you want it to be, AND draw water one tile inside/above that area (where you want the base and edges of the wall to be). Then on a different, blank area of the map, draw the wall. Now, hold down the shift key, and with your mouse, right click on one corner of the wall and drag the mouse to the opposite corner of the wall, so you've selected the whole wall while holding down the shift key. No go back to your water, and again holding down the shift key, click with the left mouse button to place the wall you've copied. Holding down the shift key tells Ace NOT to redraw the water or put edges in.