How do I find the molarity of NaOH? I need to to find how many moles of it I used when I measured how many liters were used.

Right.



Usually, the procedure is to weigh out a high molecular weight acid and place that in a flask.



You titrate that with standardized NaOH. This is the equation for the titration (unless there is more than one acidic H on the acid).



From the equation you know that one mole of NaOH reacts with one mole of acid so the number of moles of NaOH that reacted was the same as the number of moles of HA (acid) that you weighed out. You measured the milliliters (liters) of base that you used.