You can find both printed and electronic textbooks in Helka. This instruction explains how you use Helka with a computer. The interface looks a bit different on a mobile device. This video has English subtitles available.
A short guide to finding textbooks in Helka:
1) Go to Helka: https://helka.helsinki.fi
2) Search for the book by name
3) Check the book's availability and location. You can see on Helka whether the book is on the library shelf or available online. If you want to borrow a printed textbook, always check the location of the book before you fetch it from the shelf.
4) Get the book from the shelf and borrow it at the library self-service machine. You will need a Helka card and a PIN code.
For more information on how to borrow books and use e-books, visit the library website: https://www.helsinki.fi/en/helsinki-university-library