Hey all, new to the forum and been trying to understand Responsive Web Design.

I have taught myself CSS over the past year, so I am no guru but I do have an understanding of it and can make my own website using it. But I am having a harder time understanding Responsive. I checked out a tutorial on it at css-tricks.com. It shows what needs to be used to define how it responds:
1 /* Smartphones (portrait and landscape) ----------- */
2 @media only screen
3 and (min-device-width : 320px)
4 and (max-device-width : 480px) {
5 /* Styles */
6 }
7 /* Smartphones (landscape) ----------- */
8 @media only screen
9 and (min-width : 321px) {
10 /* Styles */
11 }
12 /* Smartphones (portrait) ----------- */
13 @media only screen
14 and (max-width : 320px) {
15 /* Styles */
16 }
17 /* iPads (portrait and landscape) ----------- */
18 @media only screen
19 and (min-device-width : 768px)
20 and (max-device-width : 1024px) {
21 /* Styles */
22 }
23 /* iPads (landscape) ----------- */
24 @media only screen
25 and (min-device-width : 768px)
26 and (max-device-width : 1024px)
27 and (orientation : landscape) {
28 /* Styles */
29 }
30 /* iPads (portrait) ----------- */
31 @media only screen
32 and (min-device-width : 768px)
33 and (max-device-width : 1024px)
34 and (orientation : portrait) {
35 /* Styles */
36 }
37 /* Desktops and laptops ----------- */
38 @media only screen
39 and (min-width : 1224px) {
40 /* Styles */
41 }
42 /* Large screens ----------- */
43 @media only screen
44 and (min-width : 1824px) {
45 /* Styles */
46 }
47 /* iPhone 4 ----------- */
48 @media
49 only screen and (-webkit-min-device-pixel-ratio : 1.5),
50 only screen and (min-device-pixel-ratio : 1.5) {
51 /* Styles */
52 }

Essentially what are you having to do different for each or are you having to program for each specifically? Or have one general layout and then modify it within these terms? Thanks for any info and help, could just be on of those days I have just read too much on it.