You need the HTML tag. That's:
[html]
The stuff you pasted
[/html]
If it doesn't work, then I might have to tweak the forum settings to allow non-administrators to use the HTML tag, but I thought I had that tag operational.
Also, remember not to preview! Post and if it doesn't work, THEN edit your post, remove the entire stuff that's between the HTML tag, and re-paste it.
If you preview your post prior to posting, the HTML tag will go wacky.