Step 1. Go to your blog >> Posting >> New Post and write everything you want to show to your reader except your Code or Script. Please make sure you use Edit Html to post your article.
Step 2. Copy the script you want to show to your reader. Let me give you the example :
<div class='post-body entry-content'>
<div style='clear: both;'/> <!-- clear for photos floats -->
Copy that code and convert it using Parse HTML generator tool. you can find it here
Step 3. Parse the code and copy the result to your edit html editor post. You can use blockquote to make it looks different.
Step 4. Publish your post and done.
Note : You can place any code or script to blogger post by using this tricks.