The Vigenère cipher (as it is currently known) was created by Blaise de Vigenère in 1585. However, it is worth mentioning that the cipher has undergone many reinventions over time and its original method is actually believed to have been created by Giovan Battista Bellaso, who first mentioned it in his book ‘La cifra del. Sig. Giovan Battista Bellaso’ in 1553.
A solution to frequency analysis
Creating the square is fairly simple. On the top line, write out the alphabet going from A to Z. On the next line, move every letter one space to the left, wrapping any over flow round to the end of the row. Repeat this for the remaining letters until you have the square shown below.