Only those users with access to the admin area of DealTrack are able to manage suppliers in DealTrack by clicking on Config at the top of the page and on Structure in the drop-down menu.
This will take you initially to the Dimensions page. You will then need to click on the Suppliers tab near the top of your screen, where you will be presented with the Maintain list page displaying a list of your existing suppliers.
You will also have access to the Configure collection page (as shown in the screenshot below). Clicking on this tab will then allow you to allocate your suppliers to a collection.