Double check and optimize swift iOS project for amateur

I am an amateur with an App idea. I want to build it myself in order to learn Swift in the process. But I am aware that I am an amateur, so I am looking for someone to help me check my code and help me solve issues I cannot figure out my self. I have finished the “Create profile and login part” of the project and it runs and is connected succesfully to Firebase. But I need help with 1) facebook login to Firebase, most of the work is done just needs a check as I am not sure it works 100% correctly 2) upload of profile pictures to firebase Cloud storage, 3) changing localizedDiscripton language to Danish is is english right now 4) how to remember that the user signed in 5) I want a full screen with navigation bar at the top, right now I have modal presentation on most viewcontrollers. 6) on UserRegisterViewController alle fields needs to be filled before the registerButton is enabled. 7) indication of the field that has not been filled. right now a red ring, but I cannot figure out how to remove it, when the user has filled the field correctly. 8) just a general clean up, if my code is not structured correctly. I use Xcode 11 and Swift 5 and I use both code and the Interfacebuilder.
It is probably som very simple tasks for an experienced developper. But I need somebody who will also write enough comment for me to understand what I did wrong. This is just part one of the project. If I find the right person, the next parts will follow as I get them done.