The item inventory has not been enabled yet - work on items is still ongoing. The only way you can currently interact with items is through Position -> Items. You can then pick them up from the ground, equip them, and store them in other items (packs and belts, for example).
If you didn't pick them up, you should head back to the shop and do so.
____________"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
Only fools and children dream of heroes.