You can attach an item to another existing item so that both items are associated with each other.

1. Click in the column next to the item that you want to attach. Hold down CTRL and click to select multiple items.
   
2. Go to Attach To > Existing Item.
   The Create new item with your selection(s) as the attachment(s) window will display.
3. Under Attach To, select which item you want to attach your item to.
4. Click OK.