To find Tahini in the grocery store you look in the condiments and sometimes spices aisle of the grocery store.
In most grocery stores Tahini is located in the part of the grocery stores aisle with the condiments or oils, or in the aisle with ethnic foods.
If you cannot find the Tahini in your grocery store then ask an associate or worker in the grocery store and they should know where it is.
In my local grocery store the Tahini is in the same aisle as the condiments such as ketchup, mustard, mayonnaise etc.
So look down those aisles in the store and you should find it.
You can also buy Tahini online and through Amazon Grocery.