Layers in iPad photoshop

Good day community period. I am using Photoshop on my iPad using the latest OS and I had a question concerning layers. On my desktop PC there's a way to add a layer and then use the screen feature in order to see both layers at the same time to combine however, I do not see any way of doing this on my Photoshop on iPad. I have two layers and I want the top layer to merge with the bottom layer, but there is no place that I can find on the iPad where can have the top layer  Merge with the bottom by using the screen feature like I can with the desktop PC. if I am missing something, please provide me instructions on how to add a layer and merge with the bottom layer so both appear at the same time. This should be a basic feature, but again I have played around with adding layers  But when I add a top layer, all I see is that top layer and I do not see the bottom merged with it since there is nothing that says screen.. Hopefully someone can help because I need this as a project. Thank you so much in advance!

- MJ