Theoretically, you will have to create a new project, then paste the folder with your app into the project folder and modify the settings file.
I believe you need to edit the settings.gradle file and add the project name like:
include ':appname', ':helloworldapp'
then modify the build.gradle to include dependencies:
Note: Modify it based on your app name, compatibility support, libraries, etc.
Additionally, use the User Guide available online to learn how to work with Android Studio: https://developer.android.com/studio/intro/index.html