Bike makers will mix and match components to be able to price the bike at the price point they want it to sell at, so Tektro brakes with Tiagra shifters does not tell us much.

You should be able to find a youtube video for your model of Tiagra. Though sometimes the youtube videos are made by someone that doesn't have a clue either but just talks good. You might go to shimano's tech doc site and find a model of Tiagra that looks similar to yours. The DM's will give the most info about it. The exploded veiw might give you a quick idea if that is your model.

Or perhaps share with us the year, make and model of your bike. And a picture is worth a lot too...........