I can't say for Skyrim, but if the Creation Kit will as similar to past Creation Kit, then it will be user friendly.
Relatively speaking of course, depending about what you're trying to achieve, and you will still need to understand how the game is built at first to know how to modify it.
Few examples (assumed from past TES Toolkit):
- Adding items on the maps. Very easy, 3D drag & drop, you just have to learn the controls about how moving the item and the 3D camera around.
- Creating basic items, duplicate one existing and modify it's statistics and visual properties to suit your need.
- Creating dungeons, it's also drag & drop building them in a 3D lego style. (not as easy at it seems for beginners
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)
- Modifying exterior landscape, is like ground molding.
- Creating quests will require you to learn the game scripting language.
One thing important if you're interested into modding Skyrim is to not give up just because you cannot do something in just five minutes. There will be plenty documention and many tutorials to go on.