Radiator

If not sure stop by a auto parts store like auto zone and ask one of the sales person to show you. You can put the alumaseal into the over flow tank but that will take a couple of days for it to start to work but if you were to remove upper radiator hose and add the alumaseal directly into the hose then reinstall will work much faster.

I don't anything about cars so can you tell me where the over flow tank is?

If you do not know just google how to add anti freeze to the year, make and model of your vehicle it will take you to sites or maybe a video on you tube showing you where the over flow tank is and also where radiator is located.

I know how to where to add coolant in my car. So I just add the alumaseal where I would put the antifreeze in, correct?

That is correct but like the mentioned earlier will take a couple of days to start to work when added to over flow tank.

Thank you so much for your assistance. 1 more final question when I add the alumaseal, do I add coolant at the same time?

If it is low on anti freeze yes add to full mark on over flow tank. Since adding to over flow tank may want to keep check on anti freeze level for a couple of day and add anti freeze if low until alumaseal has a chance to work.