The left block border can be changed use #gl_extra which is found in style.css

#gl_navigation {
background:#CCC;
border:4px solid #FF0000 !important;
float:left;
margin-left:-100%;
width:14.80em;
height:1%;
}

The right block border can be changed use #gl_extra which is found in style.css

#gl_extra {
background:#CCC;
border:1px solid #FF0000 !important;
float:left;
margin-left:-14.97em;
width:14.80em;
height:1%;
z-index:10;
}

The right block background can be changed using #gl_extra in style.css

#gl_extra {
background:#FF0000 !important;
border:1px solid #CCC;
float:left;
margin-left:-14.97em;
width:14.80em;
height:1%;
z-index:10;
}

The main content border can be changed in style.css using

#gl_container_fixed { /* if you adjust the width and use the forum plugin, also adjust
background:#FFF;
0 repeat-x !important;*/
min-width:955px;
width:95px;
margin:20px auto auto;
border:5px solid red;
}


The spacing over the content and beneath the header can be changed in style.css using

#gl_wrapper {
float:left;
margin-top:100px;
width:100%;
min-height:450px;
}

Similarly you can control the space between the top of the left and right blocks by putting in

#gl_navigation {
background:url(layout/smoothblue/images/smoothblue_left_block_bg.gif) 0 0 repeat-y !important;
float:left;
margin-left:-100%;
margin-top:10px !important;
width:14.80em;
height:1%;
border:0px !important;
-webkit-border-radius: 10px !important;
-moz-border-radius: 10px !important;
}
#gl_extra {
background:url(layout/smoothblue/images/smoothblue_right_block_bg.gif) 0 0 repeat-y !important;
float:left;
margin-left:-14.97em;
margin-top:10px !important;
width:14.80em;
height:1%;
z-index:10;
border:0px !important;
-webkit-border-radius: 10px !important;
-moz-border-radius: 10px !important;
}

The space between the top of the content block can be set with

#gl_content {
background:#CCC;
height:100px;
height:1%;
margin:0 15.79em;
margin-top:14px !important;
border:1px solid #979996 !important;
}

The rest of the background can be changed in syle.css  for a fixed and fluid width site using

#gl_container_fixed { /* if you adjust the width and use the forum plugin, also adjust #gl_container_fixed div.php below */
background:#FF0000 !important;
min-width:955px;
width:95px;
margin:20px auto auto;
}

#gl_container_fluid {
background:#FF0000 !important;
min-width:95px;
margin:20px;
}

The background image can be changed in style.css using,

body {
background:#FF0000 !important;
font:76% arial,verdana,tahoma,helvetica,sans-serif;
text-align:left;
margin:100;
padding:100;
}

Any solid colour background can be replaced with an image background using,

background:url(layout/nouveau/images/image_name.png) 0 0 repeat-x;

Instead of the usual,

background:#CCC;

Note that repeat-x repeats the image horizontally and repeat-y repeats it vertically.

The Content background can be changed using, in style.css

#gl_content {
background:#FF0000 !important;
height:1%;
margin:0 15.79em;
}