If you've previously uploaded an item to KCWorks and you'd like to add it to a collection, you can do this by going to the item's record page.
On the right side of the page, select Submit this work to a collection. A pop-out menu will grant you the ability to submit the work to a collection. The next screen will allow you to search for the collection you'd like to add the work to.
Once you've identified the collection, choose the Select button. The next screen will warn you that the collection's administrators have the ability to edit the work and immediately publish it. Check the boxes on the page and choose Submit record for review once you're ready.
Once you complete these steps, the record page will change to reflect that the work has been added to the collection.
In KCWorks, you also have the ability to add a work to multiple collections. You can toggle this on from the same space by selecting the Manage collections for this work button.