I think your particular problem isn't how to use Glyphicons but understanding how Bootstrap files work together.
Bootstrap requires a specific file structure to work. I see from your code you have this:
<link href="bootstrap.css" rel="stylesheet" media="screen">
Your Bootstrap.css is being loaded from the same location as your page, this would create a problem if you didn't adjust your file structure.
But first, let me recommend you setup your folder structure like so:
/css <-- Bootstrap.css here
/fonts <-- Bootstrap fonts here
/img
/js <-- Bootstrap JavaScript here
index.html
If you notice, this is also how Bootstrap structures its files in its download ZIP.
You then include your Bootstrap file like so:
<link href="css/bootstrap.css" rel="stylesheet" media="screen">
or
<link href="./css/bootstrap.css" rel="stylesheet" media="screen">
or
<link href="/css/bootstrap.css" rel="stylesheet" media="screen">
Depending on your server structure or what you're going for.
The first and second are relative to your file's current directory. The second one is just more explicit by saying "here" (./) first then css folder (/css).
The third is good if you're running a web server, and you can just use relative to root notation as the leading "/" will be always start at the root folder.
So, why do this?
Bootstrap.css has this specific line for Glyphfonts:
@font-face {
font-family: 'Glyphicons Halflings';
src: url('../fonts/glyphicons-halflings-regular.eot');
src: url('../fonts/glyphicons-halflings-regular.eot?#iefix') format('embedded-opentype'), url('../fonts/glyphicons-halflings-regular.woff') format('woff'), url('../fonts/glyphicons-halflings-regular.ttf') format('truetype'), url('../fonts/glyphicons-halflings-regular.svg#glyphicons-halflingsregular') format('svg');
}
What you can see is that that Glyphfonts are loaded by going up one directory ../ and then looking for a folder called /fonts and THEN loading the font file.
The URL address is relative to the location of the CSS file. So, if your CSS file is at the same location like this:
/fonts
Bootstrap.css
index.html
The CSS file is going one level deeper than looking for a /fonts folder.
So, let's say the actual location of these files are:
C:\www\fonts
C:\www\Boostrap.css
C:\www\index.html
The CSS file would technically be looking for a folder at:
C:\fonts
but your folder is actually in:
C:\www\fonts
So see if that helps. You don't have to do anything 'special' to load Bootstrap Glyphicons, except make sure your folder structure is set up appropriately.
When you get that fixed, your HTML should simply be:
<span class="glyphicon glyphicon-comment"></span>
Note, you need both classes. The first class glyphicon sets up the basic styles while glyphicon-comment sets the specific image.