How would you make up 100 ml of a 0.10 m nacl solution?

There are a number of ways to express concentration of a solution. This includes molarity. Molarity is expressed as the number of moles of solute per volume of the solution. 

0.10 M = 0.10 mol NaCl / L solution (0.1 L) = 0.01 mol NaCl ( 58.44 g / mol ) = 0.5844 g NaCl needed

Therefore, to prepare the solution, you need to dissolve 0.5844 g of NaCl to 100mL water.