Command LIne

Use Command line or righ click and properties but disk must be in NTFS Format and other thing if u incrypt something then u can decrypt from any other user its security but also can be problem in case of windows loss or if u take file some where.
for command line USE
Cipher Displays or alters the encryption of folders and files on NTFS volumes. Used without parameters, cipher displays the encryption state of the current folder and any files it contains.

Syntax
cipher [{/e|/d}] [/s:dir] [/a] [/f] [/q] [/h] [/k] [/u[/n]] [PathName [...]] | [/r:PathNameWithoutExtension] | [/w:PathName]

Parameters
/e
Encrypts the specified folders. Folders are marked so that files that are added to the folder later are encrypted too.
/d
Decrypts the specified folders. Folders are marked so that files that are added to the folder later are encrypted too.
/s: dir
Performs the selected operation in the specified folder and all subfolders.
/a
Performs the operation for files and directories.
/i
Continues performing the specified operation even after errors occur. By default, cipher stops when it encounters an error.
/f
Forces the encryption or decryption of all specified objects. By default, cipher skips files that have been encrypted or decrypted already.
/q
Reports only the most essential information.
/h
Displays files with hidden or system attributes. By default, these files are not encrypted or decrypted.
                                                                
/k
Creates a new file encryption key for the user running cipher. If you use this option, cipher ignores all of the other options.
/u
Updates the user's file encryption key or recovery agent's key to the current ones in all of the encrypted files on local drives (that is, if the keys have been changed). This option only works with /n.
/n
Prevents keys from being updated. Use this option to find all of the encrypted files on the local drives. This option only works with /u.
PathName
Specifies a pattern, file, or folder.
/r:PathNameWithoutExtension
OR USER PROPERTIES