The Place Of The French Adverb

Adverbs are invariable. (It would need a whole book to explain the variations of tout, and not everyone would agree with the conclusions.)

You use an adverb to express the way (you think that) a thing is or is done.
C'est un pays riche.
C'est un pays incroyablement riche.
C'est fait.
C'est bien fait.

The adverb comes next the word it modifies;
either before when it modifies an adjective:
Cette très belle fille est ma soeur
or after when it modifies a verb:
Le film dure longtemps.

When the adverb modifies the sentence (when you give your opinion on the fact you express), it may come at the beginning or at the end of the sentence.
Malheureusement, il a plu cet été.

It may come in other places, but to do so without expressing something else that what you want requires a deep knowledge of the language:
Miraculeusement le prix du pétrole n'a pas augmenté.
Le prix du pétrole n'a, miraculeusement, pas augmenté.
Both sentences mean that, despite what was expected, the price of oil did not increase (it was a kind of miracle).
But the sentence below means that the price did increase, and that the increase had been planned (it was not a "miracle"):
Le prix du pétrole n'a pas miraculeusement augmenté.

As long as you do not master the language, put the adverb that modifies a whole sentence at the beginning of it.