When I launch my web browser I find that it tries to open a web page which is no longer available. How can I change the default page which my browser accesses?

The iMac comes preconfigured to use Internet Config which contains default settings for the internet applications pre-installed on your iMac. To modify the default home page for your browser, open Internet Config and select World Wide Web. You can then change the default home page to the page of your choice.

You can change the default home page from within your browser application by unchecking "Use Internet Config" in the Preferences section if you so desire.