Step 1: Add 10g of NaCl to solution (gradually so that the crystals can dissolve):

Step 2: Add water to dissolve (making sure to get all of the NaCl off the sides of the volumetric flask):

Step 3: Fill up your flask to the base of its neck with water:

Step 4: Top it up to the line with the water bottle (making sure to read from the bottom of the meniscus):

Step 5: Find your concentration/molarity: