anarresti on "How to use Image Replacement Code"

Hi,

I want to replace the title of my blog with an image.
This is my blog: http://opapeldasnoticias.org/

http://css-tricks.com/css-image-replacement/
This post shows different codes for Image Replacement.
Because I am not good with HTML and CSS, I cannot figure out how and where to use the code.

Also, my wordpress template code seems to be using a different sintax.
If I were to use the following code, where should I put it?

-------------------------------------
<h1 class="technique-four">

<img src="images/header-image.jpg" alt="CSS-Tricks" />

</h1>

h1.technique-four {
width: 350px; height: 75px;
background: url("images/header-image.jpg");
text-indent: -9999px;
}
------------------------------------

Thank you for your time.