Okay, your question is extremely vague but I'm assuming you're talking about Cascading Style Sheets. I'm assuming you know at least a little bit about HTML.

Pretty much all CSS is designed to do is change the look and feel of a website. For example, body{ PUT CODE HERE! } would allow you to change properties of the entire document. There's a full list of properties you can manipulate here. For example, if I wanted to make the background black, All I would have to do is: body{ background-color: #000000; }

A color mixer can be found here.

Anyway, the idea is, you have it in this format: property: value; The property, then a colon, then it's value, followed by a semicolon. You can change more than one property too: body{ background-color: #000000; border-left: 100px; } Anyway, you can change a whole bunch of properties in a document. It isn't limited to the "body" part itself. For example, if you wanted to change the properties of a link you would use this code: a:link{ color:#FF0000; } a:hover{ color:#AA0000; text-decoration:underline; } The reason why I put "a" in front is because if you looked at the HTML source of a website, you'd notice the code for a link kinda looks like this. <a href="http://google.com">Display text</a> Display text

The <a> thing is called a tag. The : after the a is the state the tag is in. When the <a> tag is a link, then make it red. If it's hovered over, make it a darker red and make it underlined. Pretty simple. Here's another example. img{ border: 3px #000000 solid; } This makes all images have a 3 pixel solid black border around them.

Now that I've got the basics out of the way, let's go to the fun stuff.

A LOT of things in web pages are defined by classes. For example, in the reddit source itself, is this code: <div class="md"> <p> Can somebody, in layman's terms, explain to me how it works. I have all the CSS to change heaps of stuff, like how many readers in a sub, something instead of "readers", remove voting for comments and posts, that kind of thing. I have access to it all and I know what does what but all I do is copy and paste, I don't know how it works, or anything. I mean, I could copy and paste some CSS to change my name to "DrunkenJedi knows jack shite about CSS" but all I'd do is take existing CSS and add in my own little message, I'd be unable to write it myself. </p> <p>TL;DR Can somebody teach me how to write this shit? :P</p> <p>Please help.</p> </div>

Notice how at the top it says <div class="md">. If you wanted to manipulate JUST the text in that box this is what you would do: div .md{ font-family: courier new; color: #FF0000; } Notice the . before the md. That means to change the properties of a <div> with the "md" class. And what that would do is make the font of your submission in courier new and have the text be the color red.

There's also this other property called ID. Nearly the same shit. For example, if something had something like <span id="foo"> this is what you would do: span #foo{ //code here } The # before the foo means to look for tags with the ID "foo".

That's pretty much the basics of it. If you want to go more in depth with this stuff check out w3schools.