What is the most logical next event?

How to decode a caesar box code
Count the number of characters in the code.
Here we have 16: g t y o r j o t e o u i a b g t
Determine how many rows you can divide the letters into equally (find the square root of the number you found in step 1.
If the square root isn't a whole number, round up).
We can put 16 into 4 rows of 4 (i.e. the square root of 16 is 4).