By dissolving one mole of sodium hydroxide in enough water to make one liter of solution.
When dealing with bases, as you are here, normality simply tells you the number of moles of reactive units, in your case hydroxide ions, per liter of solution.
Sodium hydroxide is a strong base that dissociates completely in aqueous solution to produce sodium cations and hydroxide anions
#"NaOH"_text((s]) -> "Na"_text((aq])^(+) + "OH"_text((aq])^(-)#
Notice that every mole of sodium hydroxide will produce one mole of hydroxide ions in solution. Since hydroxide ions are the reactive units for bases in an acid - base reaction, also called equivalents, you get that
#1color(red)(cancel(color(black)("mole NaOH"))) * "1 mole equivalents"/(1color(red)(cancel(color(black)("moles NaOH")))) = "1 mole equiv."#
So, a 1 normal sodium hydroxide solution is the same as a 1 molar sodium hydroxide solution.
Assuming that you want to make a 1-L solution, you would weigh 40.0 g of sodium hydroxide and dissolve it in about 500 mL of water.
After the solid is completely dissolved, add enough water to get the total volume to 1 L.