I recommend not using dropbox as I had problems getting my game to work on Google chrome when using dropbox as a host.
Go to Kongregate,
Click Upload a Game,
Type in your games name and description,
At the top of the next page check the "Iframe box",
Paste the link you copied from step 1 into the Iframe url box.
Now set your game dimensions and set Plugins to "none",
Choose your game options then click Upload Iframe