Space between module elements in left or right col

In which .css file can I add a space between module items or its been assigned to left or right column and where in the .css file?
example would be great.
Thx

In template_css.css you have this:

column_right div.moduletable, .column_left div.moduletable {
margin-bottom: 20px;
}

by default there is only margin-bottom: 20px; but you can define all other margins as you need.

what would be the code sysntax then, I don't it, margin-...? It is not margin-top but in between the modules to split the grey area between the modules a bit
Th

.column_right div.moduletable, .column_left div.moduletable {
margin-bottom: 20px;
margin-top: ??px;
margin-left: ??px;
margin-right: ??px;
}

Changes towards these margins do not affect the left column items in the way I thought.
Here is the link: joomla.bc-marburg.de. If you look at the left column with grey background there are 3 news feeds. I would like to between those newsfeeds a margin so that the blue background is viewable and that those feeds do look as they are seperated blocks.
Thx

can you illustrate that somehow or better describe?