How do you draw a Newman projection for hexane while sighting down ##C_2-C_3##?

You follow a series of steps.

Step 1. Draw the structure of hexane.

Step 2. Convert it to a wedge-dash structure at ##"C-2"## and ##"C-3"##.

Step 3. Identify the groups on ##"C-2"## and ##"C-3"##.

The main chain of hexane is the horizontal zig-zag line of carbon atoms.

##"C-1"## is on the left.

The groups on ##"C-2"## are ##"H"##, ##"H"##, and ##"CH"_3##.

Those on ##"C-3"## are ##"H"##, ##"H"##, and ##"CH"_3"CH"_2"CH"_2##.

Step 4. Draw a template for a Newman projection.

Step 5. Attach the groups to the carbons of your template.

View the molecule from the upper left.

The groups on ##"C-2"## go on the front carbon atom. Put the ##"CH"_3## group on the bottom. The two ##"H"## atoms go on the other bonds.

The groups on ##"C-3"## go on the back carbon. The bulky ##"CH"_3"CH"_2"CH"_2## group goes on the top, and the two ##"H"## atoms go on the other bonds.

This is the most stable conformer, because it has the bulky methyl and propyl groups anti to each other.