Tell me how to make Caesar's Cipher, there is an idea, I need help!

Question

First we take the whole alphabet, alp = 'a, b, c, d, ....), etc., then, we get the user input, then we find these letters in alp, and +1 should go to each letter , i.e. write the letter one forward, change it to the one in front and so each letter, depending on the size, you need to use a function that takes everything from input
Next, we send the finished answer, the received answer = result
print (result)

Answer 1

Take a look at the codes in the comments of this assignment.
https://www.sololearn.com/learn/13844/

Answer 2

The good ideas, but, everything is complicated there when the head has a light construction