No Problem Red .... did not explain it the best ....
baically my problem was that using '~/' or just '/'
did not seem to be referencing the root of my .net site
i wanted to be able to link to a stylesheet using by linking to it in my master page (master page in .net can contain menus, functionality, icons etc that you would like to appear in every page in your site.... any code, links etc in the master page are included in any child pages). I needed this link to reference the stylesheet from the root of my site in order for it to work in any pages that were put in a subfolder in my site structure.
Found out that the problem is that the root folder name must be used in the path .....i.e the path '/mySitesRootFolderName/Css/myStylesheet.css' worked.
Thanks a million for everybodys help