There are two ways, one is a simple which is best suited for beginners(like me) and the other is the advancedmethod which gives your code box a more look but requires a little source tweaking.
So here's the simple method, just paste this code on your post editor in Edit HTML tab.
<textarea name="textarea" cols="40" rows="4" wrap="VIRTUAL">
Here's an on where to post :
And here is the result:
It's just the simple version, but if you want it Professional Code Box look, follow thissecond method.
1. Follow this guide on How To Edit Your Blog Template
2. Find(CTRL+F) ]]></b:skin>
3. Add this code ABOVE ]]></b:skin>
4. Click Save Template
5. Now go to your and make a new post on the blog where you added theProfessional Code Box.
On Edit HTML tab, just paste this code:
(refer to the image above for reference)
Here is the result:
Note: You cannot see the Professional Code Box on your post editor, so you'll have to save it and view the post from your blog.