In the Haworth projection why is the CH2OH group pointing up?

The CHOH group is up because you have to rotate C-5 about the C4-C5 axis to form the ring.
Here are the two projections of D-glucose.
All the groups on the right-hand side of the Fischer projection are down in the Haworth formula and the groups on the left-hand side are up.
It looks as if the -CHOH group should be down. Why is it up?
Let’s start with the Fischer projection. All the horizontal bonds are wedges.
It is easier to see the orientation of the vertical bonds if you turn the Fischer projection 90 and look at a side view of the structure. This gives us the curved backbone shown below.
To form the hemiacetal the OH group on C-5 must be in the same plane as C-1. We must rotate C-5 120 about the C4-C5 bond.
This makes the bond to the -CHOH group a wedge and positions the C-5 OH group for attack on the carbonyl group at C-1.
To get the Haworth structure we turn this projection onto its side.
The video below shows how to convert a Fischer projection of galactose to a Haworth projection.