When the editor is done loading the game files, you will probably see a pop-up warning you about a navmesh error.
THE CREATION KIT SKYRIM MODS
(You can find out more about creating and using simple mods in the Creation Kit starter tutorial linked to earlier.) Depending on your machine it may take anywhere from half a minute to a couple of minutes for the editor to load everything. Open the Creation Kit and load the game files in the Data browser: go to File, Data., and double-click the Skyrim.esm and Update.esm so that a little x appears in each of the boxes.