There are two ways to search the UIUC Library catalog. Both offer the same content but the method of searching and presentation of results varies.
Getting the actual book: When you locate your item you have two choices.
You can request the item and pick it up at any of the departmental libraries. Or, you can retrieve the book yourself from either the main stacks or the departmental library where the book is located. If you choose this option, make sure you jot down the location and call number of the item.
Access will depend on the publisher. In some case you will be able to download full books via PDF. In others you might be able only to view the book online. In all cases the Library follow the publisher's requirements.
Once you have verified that the book you are looking for is either not located in the UIUC catalog or all copies are checked out, you may order it through VU Find Catalog. Items typically arrive within 5-10 days and you will receive an email when the item is available for pick up.
If the item is not available in the Illinois catalog and it is not available through I-Share, then your next stop will be Interlibrary Loan and Document Delivery. First, keep your full citation handy -- you'll need it. Second, login to the ILLiad server using your NetID and password. From the ILLiad main menu, select "Request a Book." Be sure to fill out as much of the form as possible, including the source of your citation. This will ensure that ILL can place your request in a timely manner. You'll be notified by email when your item is ready to be picked up.
WorldCat -You can search WorldCat to find books on your topic, which might not be in the UIUC nor the I-share catalog. Once you find a title of interest, you can order it through Interlibrary Loan