well depending on what you installed is where you should put the 'code' files. If you selected blackcandy then there should be a _config.php file in the mysite/ folder. Then you should put your PHP in the mysite/code/ folder otherwise if you selected the tutorial open then the _config.php file will be in tutorial/ and you need your code in tutorial/code/
Ah yes, that's done it. I copied the StellaPage.php file to the mysite/code/ folder & that worked. Thank you.
So, if I'd like to change the default page behavior, I can modify mysite/code/Page.ss? Or is it always best to make a new Page type?
Well it depends what you want to do. Ultimately if you want to do something that is going to be on most pages then do it on Page.php or if the page requires a template thats quite different to the 'standard' eg a Home Page then its easier to make a page type for it.
Same with if you have 'sections' of a site. Eg a News section then you would make a NewsHolder.php file and a NewsItem.php file. The newsholder which holds all the News and the news page is each article.