Tiled is meant to be a tile map editor, not an editor of actual tiles.  Use a drawing program for that. :)

Can I just add that Tiled is AWESOME!  The export to json feature is the best.  I write HTML5 games, and, after Emacs, it is the single most useful tool I have.

Do you know of any introductory material on HTML5 for games? (I prefer my tutorials to be text rather than to video, by the way, though I'll entertain both)

I used the JawsJS game library to make my game.  There are several examples provided, so I just pulled a few examples apart and went from there.

http://jawsjs.com/

There are a lot of other javascript game engines and libraries, all with various states of documentation and tutorials.

Here's a list: https://github.com/bebraw/jswiki/wiki/Game-Engines

I tired Crafty, but I couldn't wrap my head around it.  I like JawsJS a lot, and I even contributed some changes to it.