How to Preseve Indentation When Save the text?

Hello Guys, I new Here, that is my first post.

The Problem

How to preverve indentation of text when save?
Can preseve my indentation? For example:

I put in to editor (mode Sourcecode) some text with codes in another languagues, just text to my readers.
<textarea>
some codes() {
do something;
}
</textarea>

but When i save they lost my lines outputing something like that some codes() { do something; }
Has something can i do? Somes happend with code

<div>
<pre>
<code>
my codes indented
</code>
</pre>
</div>

thanks all!