Install

1. Just copy paste this path in your explorer

%AppData%\Roaming\Notepad++

1. Which will expand to

C:\Users\<user name>\AppData\Roaming\Notepad++

1. Now browse to

\userDefineLangs

1. Paste the attached file into this directory.
2. Now restart Notepad++. Ready!

You can now enjoy Structured Text syntax in Notepad++ as shown below