Welcome to the forum.
All of the methods that you describe would be valid ways of selling your notes. Keep in mind that dealers are trying to run a business and so might offer you less than catalogue price for your notes.
It is always wise to be cautious when buying online. I don't do it myself, simply because I like to see and feel the notes in person.
If you want to sell on the forum, you must have a minimum number of posts before that option will become available to you. Once it is, be sure to include a detailed description and scan of the note(s) you are trying to sell.
That's it!
Dean