Help with programming to decide if user input is string or integer?

Hey everyone! I am having a bit of trouble with this program of mine I am doing because why not. I am new to coding so its a relatively (should be) simple journal or diary program.

I would like the program to determine if what the user inputs is a string or integer and respond based on that. Ive tried looking this up but i just keep seeing varied and confusing answers that I have trouble getting to work.