How to make a custom web plugin [on hold]

I am trying to find information on how to get started on developing a custom web plugin, something along the lines of Miniclip’s game manager, vlc video player, etc. Essentially what I want to do is create an image of a guitar fretboard and generate quizzes based around guitar scales, chords, modes etc. Where the user can click on notes, sections of the board can light up in different colours, etc., etc., but have it as modular as possible. Can I use jQuery or should I use something else? Also, am I thinking in the right terms, i.e. using a plugin or should I be thinking of HTML/jQuery or something different entirely. I’m not opposed to modifying an existing open source plugin already available so if that's an option let me know. I am happy to learn whatever suits, so how would you guys tackle this?