How to create an app in android studio??

Answer 1

program it, maybe?
seriously, there are beginner friendly tutorials on that by Google developers. just search for them. there are also video tutorials on YouTube. from basic hello world apps (which is included by default in Android studio) to galleries, contact management etc.

Answer 2

There is quite a large learning curve between completing a SoloLearn tutorial and creating a fully functional Android app.
Best bet is to think of a simple application, and find a tutorial on how to make it. Then add bits on and just practice, until you're confident you can make your own.

Answer 3

you need to learn java.