It's pretty easy to use.
Clique allows you to set up your spells in your spell book to mouse clicks and you can use those on unit frames. For instance these are my bindings:
Ctrl + left click = FoL
Ctrl + right click = HL
Ctrl + middle click = Holy Shock
Shift + Left Click = Cleanse
Shift + Right Click = BoF
Shift + Middle Click = BoP
Alt + Left Click = BoSac
Grid puts all of the members in your raid in a nice little rectangle. Your parties will be arranged in rows or columns, with the first 4 letters of their name in the middle by default. The fill background behind the player is their health, and as it lowers (or rises, configurable) they get closer to dieing. When they get any kind of debuff on them, it displays in the middle of their portrait. It comes with showing poisons, diseases, magic, and curses. But I recommend disabling Curses since you cant do anything about them anyway. It will also have little squares in the corners to notify you of other things including incoming heals and aggro, and you can configure it for even more. One configuration I like is that I alpha out the square if they are more than 40 yards away from me, so I know they are out of my range. Useful in PvE but VERY useful in PvP.
So with Grid + Clique, all you need to do is click onto the grid with your assigned clicks and it will do that spell on them. For me it's just a game of "Keep the little squares clean and full by clicking on them"
Just play around with it, doesn't take very long to learn how to use the addons.