By no means a perfect UI, but a good example of what you should be shooting for. Unlike some UI posts, which give you a cookie-cutter UI to build yours around, I'm going to tell you what makes for a great healer UI and let you build your own. Using a pre-built UI is kind of like wearing somebody else's pants...it never quite fits and you're always adjusting the crotch. When you build your own UI there's a certain sense of innate familiarity to it because you made the decision to put things where you put them.
Healer UIs are slightly different than other class' UIs because of the fact that our eyes are inevitably drawn to our raid frames. If you use a click-to-heal mod like Clique, you'll be spending 95% of your time clicking on those small colored boxes, so you need to make sure they're visable and in a central location. Putting them off to one side or another can pull your eyes away from the action on the screen and cause you to stand in void zones, fire, or other environmental hazards. I place my Grid window right underneath where my character is on the screen so that my eyes are never far from my feet for fear of swirling black voids of doom.
Another important thing is having easy to read unit frames. Unit frame mods will display all sorts of great and potentially useful information, but if they're too cluttered you'll never be able to figure out something as simple as "How much health does my tank have?" You want to be able to get a read on your target's health, your health, and your mana with just a momentary flick of your eyes. Any longer and somebody could die.
A mod that is practically required for raid healing is Decursive, which turns cleansing into a whack-a-mole type game. The small colored boxes between Grid and Recount and my decursive boxes and they light up when people get debuffs I can remove. Position these somewhere that's easily accessable, as some debuffs don't give you much time to remove before it's too late. I like to keep mine next to Grid so the mouse travel time is short.
This might seem redundant, but I like to have party bars open all the time. As a resto shaman you'll find yourself beholden not only to your own mana bar but also to the mana bars of your party memebers, as mana tide totem only works for your party. Having party windows open lets you quickly get a read on your party's mana so you can drop mana tide at just the right time and not when your party is all sitting at 95% mana.
From there it's just a matter of trying to make something that you like. Include the information you need to function as a healer. I try to keep it simple and uncluttered so I have the best chance to see what's going on without interruption.
The most important piece of information I can give somebody who is designing thier UI is that a UI should assist in your healing, not dominate it. If a mod is taking up too much real estate or spamming you with annoying messages, get rid of it. With the exception of a few core mods, you can do fine with any setup as long as you're comfortable with it.