You can't upload to anywhere but Scratch. There is a way, though, to show a project you've made embedded in HTML.
<object width="483" height="387" type="application/x-shockwave-flash" data="http://alpha.scratch.mit.edu/scratchr2/static/Scratch_new.swf"> <param name="allowScriptAccess" value="always"> <param name="allowFullScreen" value="true"> <param name="flashvars" value="project=http://scratch.mit.edu/static/projects/USERNAME/PROJECT_ID.sb?version=VERSION#/"> </object> </div>
<applet id='ProjectApplet' style='display:block' code='ScratchApplet' codebase='http://scratch.mit.edu/static/misc' archive='ScratchApplet.jar' height='387' width='482'><param name='project' value='../../static/projects/USERNAME/PROJECT_ID.sb'></applet> <a href='PROJECT URL GOES HERE'>Learn more about this project</a>
In the all-caps part, you replace this text with what it says. So like where it says "USERNAME", put your Scratch username. Note that VERSION# is the number of times you've reloaded the project. If you've only uploaded once and not updated the project at all, then put 1 here.
For more info go to this wiki article
And I think this should go in the Questions about Scratch forum. I'll have it be moved for you.
Look on the right side of the project page where it says "Embed". One of the options is Facebook.