I would use a mod manager if I were you.
After you extracted the rar file did you open it and move the files to the Data folder individually?
You cannot just plunk the file into your Data folder, the file should have an .esp "Elder Scrolls Plugin" or esm "Elder Scrolls Master" file and other files like mesh and texture files depending on the mod that must be added to your Data folder and in some cases will overwrite files already there, or not depending, once again on the mod.
Unless you are an experienced modder you would be rather foolish to download mods manually, use a mod manager.
Unless the esp or esm file is in your Data folder I do not believe it will show up in the CK.