The template does not become part of the skin so nothing happens to it. It is used as a reference for creating a skin.

CSS boils down to selectors and rules, rules are the part within the {} and the selector is the part before {} which determines which elements the rules are applied to.

.foo { font-weight:bold;}

means all elements with the css class named foo will be bold

div table a { color:blue; }

means all a elements inside a table that is inside a div will be blue

This is just 2 examples, understanding the different kinds of selctors is crucial which is why I recommend you read a book on CSS.

You cannot use the selectors from the templates, only the rules, so usually its a process of harvesting the rules from the template and putting them in appropriate selectors for mojoPortal. mojoPortal uses its own specific class names and there is no way to integrate arbitrary ones from the template so the selectors for a mojoportal skin are never going to be the same as the ones in the templates.

By using existing skins as a starting point, many useful selectors are already defined and you just need to replace the rules appropriately in the right places and in some cases you need to add or refine selectors.

Hope it helps,

Joe