What is fluid layout?

Without writing a whole report on how to make images scale, your current course and the "Build a Responsive Website" course should give you a better understanding of how scalable images and fluid/responsive design work together.

In short fluid layouts adjust to the browser's viewport. Webpages and content resizes to fit different screen sizes and allows more flexibility for everyone trying to see your site.

The Responsive Design stage can show you how.

Add the appropriate CSS code to the CSS to make images scale with the fluid layout i am stuck in this code challenge cant understand i am trying @media screen and (max-width : 480px) { .cupcake img { display: none;}
}

@media only screen
and (max-width : 480px) {
     .cupcake img { display: none; }
}

Your sample states that if the viewport is at 480px or smaller the image with the class cupcake will not be shown. Basically no image to scale. You may need to change the display: none; part to something else =).

may be i need to put something like this grid_1,grid_2......grid_12

So basically the challenge is asking you to make the image with the class of cupcake scalable. Right now the example you gave sets the image not to show. In order to make an image scalable you would have to change its width to a percentage. From the video you watch this should be pretty straight forward.

Hint display:none; should be changed out to something else. I would love to just give you the answer but it only gets more difficult in later exercises if you don't understand this. If you don't get it take a break, come back to it at a later time if necessary. I had to do that and watch the video a few times before I got it. It pays off though trust me.