When you buy items with silver, they first appear as a package in your consumables screen. From there, you can choose to refund the package for up to seven days, or you can open it. Once you open it, the contents become available for use. In the case of ornaments, the will appear in your inventory in the screen below your consumables. In that screen, you can choose the unlock option on each ornament, which will remove it from that screen, purely to free up space on that screen. The ornaments will appear in the customaztion screen of any applicable weapons or armor.