Install VeryAndroid File Protector for Tablet on your Android Tablet.
Download VeryAndroid File Protector (a zip file) onto your computer first from our website and then unzip the file. You will see a file called FileProtectorForTablet.apk. Copy it to your Android Tablet and install it with an app manger program such as AppInstaller.
Go to the Market (Google Play) on your Android Tablet and search for VeryAndroid File Protector for Tablet. Download and install it on your phone directly.).
Run the VeryAndroid File Protector for Tablet on your android Tablet and you will see this screen:
Here you can select the file/folder you want to encrypt and protect. Click the file or long click the folder and you will see this screen:
Click Encrypt File, enter your password then click "Encrypt" to continue:
Done. Now the file/folder have been encrypted and locked.
Nobody will be able to access these protected contents without your password.
Note: To unlock the password protected files/folders on your Android Tablet, please refer HERE