You use a slightly different technique to insert a button into a document than you do to embed a PDB file, understandably enough.

<embed type="application/x-spt" width="20" height="20" button="push" target="themol" script="YOUR COMMANDS HERE">

embed tells the browser that you're calling a plugin of some kind
type="application/x-spt" tells the machine it's a chime script
width="20" height="20" tells the machine the desired dimensions of the button (in pixels)
button="push" tells the machine what kind of button we're using (push is the simplest - we'll start here)
target="themol" is to tell which molecule we're working on - but we only have one, so don't sweat it
script=" " is where we actually issue commands to Chime - the important part!

OK - that is certainly a lot of information.  But, once again, don't panic - I'm about to make it a whole lot easier!