Magic effects can be found in the "Object Window" of the Creation Kit in WorldObjects → Static → Magic:
From the list on the right, quite a few effects can be chosen, ranging from the small
icons you see in the in-game Magic menu (on the right in the picture below), to larger animated effects (to the left on the ground and in the back):
As the category implies, these are static, and will remain wherever they are placed.
With clutter, the process is a little more extensive.
Clutter like cutlery, dishes, cups, plates, et cetera, are usable items, and therefore inherently dynamic.
Clutter can be found in the "Object Window" through Items → MiscItems → CLUTTER:
Since these items are dynamic by nature, they somehow need to be converted to become static.
Using the fork in the image above as an example, there are two ways to do so:
After placing the item, you can add scripts to the reference to make it unreceptive to Havok-induced physics.
In the "Reference" window, go to the Scripts tab (underneath the Encounter Zone drop down menu, all the way at the end of the tabs), and pick
defaultDisableHavokOnLoad through the Add button:
I'm not sure if this next step is necessary, but you might also want to activate the 'Don't Havok Settle' flag at the bottom of the "Reference" window (in the "3D View" or the "Cell View"), as this will prevent the item from settling (falling) once it's cell is loaded in-game:
Alternatively, you can create a new static object using the model of your choosing.
Using the "BasicFork01" item as seen in the last screenshots, double-click the Editor ID entry (i.c. 'BasicFork01'), and the "MiscItem" window will show up. Under Model, select the contents of the box (consisting of the location and name of the .nif model file), and copy it (using Ctrl+c, but preferably using the context menu, since the shortcut often does not seem to work with me):
Now, go to the Static items list, right-click the area where the contents of the folder you want your new item to be part of are shown, select 'New', and name the new item in the "Static" window that appears.
Then go to 'Edit' right of the 'Model' box, and, in the "Model Data" window that appears, to 'Edit' right of the 'Model File Name'. The "Select NetImmerse Model" window will pop up. Go to the /Meshes folder in Skyrim's /Data folder, and paste the copied path in the File Name box:
If all went well, the model you want should show up now.
Save all, and you will have a new static item using the desired 3d model to use in-game.
While the first method is easier, the second will make sure nothing unwanted happens to your decorations, as they won't be referenced by other mods.