You must be logged in and on the search results screen before you can place a hold.
Click on the checkbox next to the item.
Click on Place Book on Hold.
Enter your email address in the box field if you would like to be notified when the item becomes available. Then click on Submit.
If you do not enter an email address you will be prompted to confirm. Click OK to continue or Cancel to go back.
You will receive a confirmation that your items was placed on hold.