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.