You can find the titles you need at https://osiris.utwente.nl/student/OnderwijsCatalogus.do Using the course codes mentioned in the study programme or admission letter. Once you know which books you need you can order them at a book store. You can also get help of the study associations. The study associations will sell you books at a reduced price. For information (see below).
You can order your books online. To do this, you need a University of Twente ICT-account, which you will receive when you enrol for your study, ánd you have to become a member of Sirius first. http://www.sirius.utwente.nl/en/books/