• Access your own blog by selecting 'Edit Your Space'
• In your browser Navigation Toolbar add to the url: &powertoy=sandbox
  

For example, the url:
http://spaces.msn.com/members/.../PersonalSpace.aspx?_c02_owner=1&_c=
becomes:
http://spaces.msn.com/members/.../PersonalSpace.aspx?_c02_owner=1&_c=&powertoy=sandbox

• Click on 'Customize' and select 'Modules'
• Add the module 'PowerToy: Custom HTML' to the existing modules.

Then You Click Save and you will have a window like the window below then if you have a html code from a picture or something  and paste it in the Custom Html AKA Sandbox

• Click on the Save button, available in the window.