Purchased a queen metal frame which came without attaching together essentials. What connecting items do I need to purchase?

This will depend on whether you are using a head and foot board or maybe you just want to have the bed without the head and foot board. It will serve its purpose either way. To use without the head and foot board, the only thing you'll need to purchase is some pine 1×3 or 1×4's for slats you'll need 5 to 6 cut to fit between the two metal pieces of angel (bed frame). After you space those out evenly, then place your box spring over them then your mattress. If you are using a head and foot board, then there should be hook-like ends on the angel - that is what slides into the slots on the head and or foot boards.