Acid/Base Titration Question?

I have a titration lab tomorrow worth alot of marks so I dont want to screw up. Its with sodium carbonate and im trying to find the concentration of the HCl. So far, I will put the sodium carbonate into the burette to the 0 mark. But my main question is the acid. I will be putting 10mL of HCl into an erlenmeyer flask with 3 drops of methyl orange indicator. Do I have to add distilled water? How much? Why? Thank you! :)