I want to be able to modify the layout of the admin page and am not sure where the css settings for this form are held. Can someone help me please?
First off, if you havent already got it (and if you do, you can find out where the css files is by using it) you should get Firebug: http://getfirebug.com/
That said, the admin is a module just like any other module you add. All its files are within the cms folder in your installation, and the css files are within... the css folder inside cms
Thanks for the info about Firebug I will download it. I am a new user of Silverstripe and have done all the tutorials. As a result I have got a set of css file on my system called form, layout and typrography. Since finishing the tutorials I have been developing my own site and as part of this I have been modifying the css files to modify the layout. One consequence of this is that the admin form's layout has been altered. This was not my intention and I wanted to understand which css file and even better which settings were being used by the admin page. I'm still getting to grips with how the system works so excuse my lack of understanding.
Ronin - you can override the cms styles by defining a editor.css in your theme. Then just override any selectors as you go in that file