my mac air (2017) screen is showing random pink line after one week

I just bought this Mac air just a week ago, and half way through today it has started showing a random pink line down the right side of the screen. has anyone else had this problem? I know that apple has a one year warranty but how do I go about swapping my computer/fixing the screen? I shouldn't have to pay having just bought the laptop, especially since it has been kept it perfect condition in that time (I haven't dropped it or anything.)