Is this Mint or Windows? Also, if you want the real deal, go get a French keyboard. It is different.
https://www.amazon.com/French-European-Language-Keyboard-Windows/dp/B0002JP05Y for example shows the AZERTY keyboard.
Doing this with just layouts would be annoying to most French. Look at that keyboard. It has the characters you were asking about.
There are also stickers for those that have a laptop.
There are also a lot of priors about adding and switching layouts. Example: https://stackoverflow.com/questions/22384513/how-does-one-add-keyboard-languages-and-switch-between-them-in-linux-mint-16