Quick Explanation:
The negative no lacks of the permutation element which means it is not movable withing the sentence. It always goes before the segment to which it is related. For example:

Nosotros no podremos ir al cine mañana. - We won't be able to go to the movies tomorrow.
Quería acostarme más temprano pero no pude. - I wanted to go to bed earlier but I couldn't.

Long Explanation:
The negation no is not only an adverb but it implies the form of a sentence.

Mario no caminó el recorrido. - Mario did not walk the route.

When the no goes before a unit that is not part of the verbal nucleus, the negativity applies only to the unit after it. For example:

Miguel siempre come pizza, pero no come hamburguesa. - Miguel always eats pizza, but he doesn't eat hamburgers.
La escritora escribió no menos de 25 libros. - The (female) writer wrote no less than 25 books.

There are other adverbs that imply negativity: nunca (never), jamás (never), and tampoco (neither, either).

They go before the verb

Ella jamás vendrá a mi casa. - She will never come to my house.

or they go after the verb when the no is placed before the verb

Ella no vendrá jamás a mi casa. - She won't ever come to my house.

Quick Explanation:
The affirmative sí differs from no because it can already be implied in the sentence. For example:

Mi secretaria trajo los apuntes. - My secretary brought the notes.

You can mention it when you answer a question.

Mi secretaria sí trajo las flores. - My secretary did bring the flowers.

Long Explanation:
The affirmative sí can be written in different places within the sentences to convey the same message. Sometimes it needs to be separated by commas.

Sí, mi secretaria trajo los apuntes. - Yes, my secretary brought the notes.

Mi secretaria sí trajo los apuntes. - My secretary did bring the notes.

Mi secretaria trajo los apuntes, sí. - My secretary brought the notes, yes she did.

There are also other affirmative adverbs that can be placed in different parts of the sentence. Let's review it using the affirmative adverb ciertamente (certainly).

Ciertamente, mi secretaria trajo los apuntes. - Certainly, my secretary brought the notes.

Mi secretaria ciertamente trajo los apuntes. - My secretary certainly bring the notes.

Mi secretaria trajo los apuntes, ciertamente. - My secretary brought the notes, certainly.