Setup Notepad++ Spell Checker

1. Download Aspell Installer and a precompiled dictionary here.
2. Install the Aspell and precompiled dictionary (English, in my case).
3. Go to Notepad++->Plugins->Spell Checker, and put in the location of Aspell, e.g., "D:\Program Files\Aspell\bin".
4. Restart notepad++ and test whether spell checker is working.