When you access a Dawsonera ebook you can choose to "Download" or "Read Online". If you select "Download" you can choose 1 day or 2 days. After the time period has expired you will no longer be able to read the book online until you download it again.
There is also an option to "Read Online". This option gives greater functionality and allows you to make notes.
You can search for ebooks using the "University Collections" search in StarPlus. Enter key words and limit your results to "Full Text Online" and "Books" using the option on the left side of the page.