Your comments

Thanks, You directed me to the issue. 

I thought that by setting the file  "syntac definition" to "css" it will automatically set the file to be .css

so my file was named screen and when I changed it to screen.css it worked! 

Thanks so much Boss

This is a snap of the html file:

<meta charset="utf-8">
<link rel="stylesheet" href="screen.css" type="text/css" />
<title>CV Page</title>
<div id="Header">
<img src="" />
<p>this is the header</p>

and this is a snap of my css file:

#Header {
color: red;
font-weight: bold;

I'm having the same issue here. Did you figure out why they won't link?