Add options in explorer context menu when some text is selected

Hi, how to add an option in this context menu ?
Imgur: The magic of the Internet

How to add UPPERCASE and lowercase like in Notepad++ ? and other options
Imgur: The magic of the Internet

I'm already doing it by pressing hotkeys with an autohotkey script but I would prefer directly from the menu like notepad++ without looking for keys on the keyboard. Any help would be appreciated.
This is the script I'm using:

Code:

!x::

store := clipboard
send ^x
clipwait
sendraw, [
send, ^v
sendraw, ]
clipboard := store
store =
return

!z::

store := clipboard
send ^x
clipwait
sendraw, (
send, ^v
sendraw, )
clipboard := store
store =
return

!l:: 
send ^c                                                               
StringLower Clipboard, Clipboard, L
Send %Clipboard%
RETURN

!u:: 
send ^c                                                               
StringUpper Clipboard, Clipboard, U
Send %Clipboard%
RETURN


!t:: 
send ^c                                                               
StringUpper Clipboard, Clipboard, T
Send %Clipboard%
RETURN