Probably the best way is on the official Scratch website at http://scratch.mit.edu
You can also embed your Scratch in a web page by publishing to the official site, and then copying the embed code from the site into your html.
Publishing On Your Own Webserver
If you want to publish your Scratches directly to your own server, you need to upload the following two files to a folder in your web:
1.
http://scratch.mit.edu/static/misc/ScratchApplet.jar
2.
http://scratch.mit.edu/static/misc/soundbank.gm
Then copy your scratch .sb file to the same folder.
Now copy the following code into the body of your html:
<applet id="ProjectApplet" style="display:block"
code="ScratchApplet" codebase="./" archive="ScratchApplet.jar"
height="387" width="482">
<param name="project" value="myproject.sb">
</applet>
Replace myproject.sb with the filename of your Scratch.

