After you have entered the password, it will be verified (with the checksum of the proper password!) and you'll see the main window of WinDefender if entered password is correct.
In the picture above, WinDefender is keeping a number of the objects (files and folders that's protected) in the list, but if you are running WinDefender first time you'll see the only two objects - system.dat and user.dat that's system registry files protected by WinDefender from being deleted (this behavior may be changed anytime from the menu Preferences).
Now it will be showed how to add new folder to the WinDefender's list and setup all necessary protection for it. Click menu "File" and select the command "Add folder".
You'll be prompted with the dialog to select a folder for adding to the list. Select a folder you would like to protect and click "OK".
As mentioned above, if you have selected the option "Produce enciphering" in the dialog "Settings for the object", you'll be prompted with the dialog that will show you the encryption progress of your files in the folder. After it click "OK" to finish.
That's all! The folder is in the list and WinDefender is doing the real-time protection for it. If you have selected encryption of the folder this is the time for you to sure that you can freely access your encrypted files from any application (Explorer, MS Word, Excel, etc.)
Anytime you can change protection you have installed. Simply right-click mouse with the object and switch the protection you wish (see the picture).
If you require permanently delete the folder from the list - select it in the list and press "DEL" button. If the folder had been encrypted you'll be prompted with the confirmation to decrypt the folder.
If you wish uninstall WinDefender you should delete all necessary folders from the list and decrypt if necessary it first. It doesn't do automatically.