Transition Small

So when I was just messing around with some twitch clips for a friend of mine. I was trying out my premade transitions which are set as 1080 x 1920, but it is still pretty small and it creates these black bars at the side. Thanks for any kind of help!

[Moderator note: please add images directly into your post so users do not need to download strange files to see them. Use eitehr drag/drop onto your reply box or the picture icon of the reply box. I fixed this post for you.]