If you want to change the CMSbyCW default Header color (darkblue or #1E4C91) to a lighter color (for this example, I will use one of the domains I am deploying, which would use the domains original website colors).  The color to change it to is a color lighter than "lightgray" or "whitesmoke".   

You just have to change two files:

1.) header.php

Go to public_html > Templates > header.php

The style to tweak is 

header,
div#header {
 background: #1E4C91;
 color: #fff;
 padding-top: 10px;
 padding-left: 10px;
 padding-right: 10px;
 padding-bottom: 10px;
 }

1.1) Change the Header background from this: 

 background: #1E4C91;

To THIS:  

 background: whitesmoke !important;

1.2) Change the Header font color from this: 

 color: #fff;

To THIS: 

 color: #1E4C91 !important;

1.3) Change the Header Navigation (Home, Blog, Pages links) font color from this: 

color: #fff;

To THIS: 

color: #1E4C91 !important;

2.) index.php

Via FTP (or your webhost's File Manager)

Go to public_html > index.php

Change this: 

<header>
<h1>Welcome!</h1>
<a href="login.php" style="color: white !important;">
Login to the CMS
</a>
</header>

To THIS:  

<header>
<h1>Welcome!</h1>
<a href="login.php" style="color: #1E4C91 !important;">
Login to the CMS
</a>
</header>

Below is a BEFORE and AFTER screenshot. 

BEFORE Customization 

(Note I just followed the Installation and Customization Instructions from the CMSbyCW Central Help Page HERE. (opens in a new page)

AFTER Customization

That's it!

You can make CMSbyCW your own customizable website!

More Features HERE.