how do i place a bed down?

[muflon]

i cant place a 2 piece bed anywhere in my base. theres plenty of room but its always red

[Shurenai]

Do you have both pieces in your main inventory? Neither piece can be held in your hands or in a backpack- They have to be loose in your inventory or on the ground nearby. If you can't hold both in your main inventory, drop one on the ground near where you want to build it.

This applies to ALL multi-piece objects.

Also, just in case, Make sure you have all associated pieces of the object. Each one is an individual item. Some people mistake the numbers in parenthesis to be the count of pieces in their inventory but it's not- The numbers represent the piece of the set and the total number of pieces in the set.
EG:
Bed (1/4)
Bed (2/4)
Bed (3/4)
Bed (4/4)
Each one of these is a unique item, and you need to have all 4 pieces, 1, 2, 3 and 4, in order to place that bed.

In your case you need (1/2) and (2/2).

[Shady Allie]

silly i know.... but i have to ask... do you have both pieces in your inventory?
not in a bag or equipped.
you need 2 pieces for a double bed. you will see 1/2 and 2/2 you need both pieces.

you may drop one on the ground as well, if it is near and you have the other one in your inventory.

[Ykario]

You only need one of the two pieces to be in your inventory, tho