Before we begin though, this is going to be a 3-post tutorial, so please wait a few minutes for the forums to let me post the second and third parts :P ...
1. What is clcInfo?
clcInfo is an addon that combines several of the most important combat functions into one small, nifty and HIGHLY customisable addon. It can track everything from buffs and debuffs to holy power, and also comes with the ability to set up a rotation tracker for several classes (with more to come). For example, I use it in PvE to track my key Ret cooldowns & procs, how much Holy Power I have, and also have it tell me which button to push next. No more staring all over my screen to track everything from Judgement's cooldown to Holy Power - I can now stick it all in the centre of my screen where I want it.
2. Where can I get it?
Curse (www.curse.com) is the best place to go. I'd also recommend getting the Curse Client, as it makes updating most of your addons a lot easier than doing it manually. Install it the same way you would any addon.
The addon's author also maintains a thread on clcInfo for paladins at Elitist Jerks. Note that most of the clcInfo stuff is at the end of the thread, as the same thread's been used for 3 different addons now (S.H.I.T., clcRet and now clcInfo). Find it here: http://elitistjerks.com/f76/t53171-ret_fcfs_rotation_helper
Finally, there is also a small wiki site for the addon: http://sites.google.com/site/clcinfowiki/home
3a. Setting it up: Templates
A word of caution before we begin. Setting up clcInfo can seem daunting. Well, it's not. An experienced LUA programmer will no doubt get a lot more out of clcInfo than anyone else, but all you need to do is follow the instructions below, use a little initiative, and spend a few minutes deciding how you'd like it all to look.
1. Type /clcinfo to bring up the options.
2. On the left hand side, choose Template 1.
3. Select Retribution and then pick a talent. I chose "Inquiry of Faith" and 3 ranks because I also have a Ret PvP spec and don't want clcInfo showing up in PvP. If you want (say) Zealotry, pick that one and just leave it at 1 rank.
4. Once that's done, you'll see a whole bunch of new options appear.
5. Note that if you're having trouble getting the layout just right, you can go to Active: Template 1 and set it to always show, under the Visibility heading. Strata determines whether or not other addons and the like can cover up clcInfo.
3b. Setting it up: Grids
1. Go to Active Template then Grids, then Add Grid. New options appear.
2. Go to Grid 1 and under the Grid tab on the right, set rows and columns to 1, and cell width and height to 50. Position controls its position in your screen - X for left / right, Y for top / bottom. In this case, I want clcInfo to appear below my character, near the centre, so let's try "X= 0, Y= -150" for its position.
3. Grid 2 is our "next ability to hit" icon. It will be smaller than Grid 1's button, and to the right of it. Notice the similarities and differences to Grid 1 - cell width / height is 40, and it's co-ordinates are 50,-155, which put it to the right and level with Grid 1.
4. Grid 3 is our cooldown monitoring box. It's got 9 cells in it (ie 1 spell / ability / item icon per cell), and they're all small and to the left of Grid 1. For this I'll just fill most of them with basic paladin cooldowns, with two exceptions - one being Hand of Light, our Mastery, and the other being Censure, the DoT from Seal of Truth. We'll cover exactly how to do these below, under the "Icons" section - for now, let's just get the grid set up.