C++ project application , to be uploaded to Microsoft store. Need security features added

I've got a application created in c++ that allows for images to be iterated onto the screen. As I'll be putting it onto a new server I'd like new security features added to make it 100% secure from hacking I'd also like small additional amendments to be made. I'll then need help adding it onto the Microsoft store to make it readily available. Il lawns you the source code so you can view