It's important that we take a moment to dissect a URL and understand the terminology. Let's take a look at an example:
In creating our web sites we need to be a bit pickier in how we name our files. Naturally this is for a reason, web servers differ depending upon what operating system they are using. Some servers are case sensitive, in other words, "index.html" is not the same thing as "INDEX.HTML". So here are a few recommendations that you should expect to follow (oh, by the way this might help reduce the headaches that occur when naming conventions cause havoc in your web site!):
There's no exception to this rule, the home page of your web page must be named index.html. Likewise, if you choose to work on more complex sites where sub-directories are used, the first page within a sub-directory should also be named index.html. If you choose to name your file another name your users will be denied that page unless they use an absolute URL to that exact location. By default on a server when someone types in a web address the server looks for an index.html file. If it is not there your users will be greeted with a page listing all the contents of your site, giving them access to all files on your server. This mistake would look similar to this:
The key to keeping things together when working on a web site is by staying organized. Organization is essential in web design, without it you'll find yourself with broken links and lost files. From the start you should create a folder for your entire site, this is often called the root folder. Within this folder you should create a folder for any images and a separate folder for CSS (Cascading Style Sheets). As you gain experience you may begin to use other technology to enhance your site such as Flash or php. Again, a separate folder for each will make your life easier. As you work on more complex sites you may even break everything down a step further and create separate directories for specific sections of a site. You should always start this organization in the beginning, changing your mind a moving things around later can affect files that are linked (yes, this is where the headaches may come in!).