Why does this code still result in cs0120?

Question

I am creating an encryption program, but the code keeps resulting in cs0120 at line 19: the definition of the string I must print.
View my code here: https://code.sololearn.com/cRfwyfoojzrB/#cs
If you can, please send an upgraded version to see that Your answer works.

Answer 1

Your code is blank?

Answer 2

Oops, didn't save - look again now

Answer 3

just add static in front of string getInput()