Please check my idea about responsive webdesign.

Not really. "Responsive web design" is a strategy for sizing and presenting web page elements. Media queries just help you achieve a responsive web design.

The only way to make your design fluid is to use percentages when setting element widths (actually, there are other relative measurements, but percentages are most common). Here's an example:

This is NOT fluid or responsive:

<style>
#myDiv { width: 400px; }
</style>
<div id="myDiv">
</div>

This IS fluid and responsive:

<style>
#myDiv { width: 50%; }
</style>
<div id="myDiv">
</div>

The second div is fluid and responsive because it will always be 50% (half the width) of the browser window.

But now you think, you really don't want that div to be 50% of the browser window if the browser window is small, like on a phone. That's where Media Queries come in. You think like, "if the browser window is less than 600px wide, I want that div to be the whole width of the window." So to do that, you'd add a media query AFTER the original css setting, like this:

<style>
#myDiv { width: 50%; }
@media screen and (max-width: 600px) {
    #myDiv { width: 100%; }
}
</style>
<div id="myDiv">
</div>

With this combination, the browser will make the div 100% of the browser window IF the window is at most 600px, otherwise it will make the div 50% of the browser window.

Voila, you're practicing responsive web design.