En mi cuarto quiero poner un estante nuevo para mis libros de español.

Because en mi cuarto sets the location: in my room.

Starting with the location is very natural in Spanish when you want to frame the sentence first. It gives a slight emphasis to where the action will happen.

Compare:

• En mi cuarto quiero poner un estante nuevo... = In my room, I want to put/install a new shelf...
• Quiero poner un estante nuevo en mi cuarto... = I want to put/install a new shelf in my room...

Both are correct. The second version is a bit more neutral in everyday speech.

Both can mean room, and in many contexts both are possible.

A few useful points:

• cuarto is very common in everyday Spanish and often means bedroom/room
• habitación is slightly more neutral or formal and can also mean room

So:

• En mi cuarto = In my room
• En mi habitación = also In my room

In Spain, cuarto is extremely common in casual speech.

Because after querer (to want), Spanish normally uses an infinitive.

So the pattern is:

• quiero + infinitive

Examples:

• quiero poner = I want to put
• quiero comprar = I want to buy
• quiero leer = I want to read

You do not say:

• quiero pongo
• quiero compro

That would be ungrammatical.

Here poner means something like:

• to put
• to place
• to set up
• sometimes even to install, depending on context

With furniture or objects in a room, poner is very common.

So poner un estante can mean:

• put up a shelf
• place a shelf
• install a shelf

If you want to sound more specifically like install, Spanish could also use:

• colocar
• instalar

But poner is perfectly natural and very common.

Both are possible, but the meaning/emphasis changes a little.

• un estante nuevo usually means a shelf that is new
• un nuevo estante often means another/new one, with more emphasis on it being an additional or newly chosen shelf

In many everyday situations, un estante nuevo is the most straightforward way to say a new shelf.

So in this sentence, un estante nuevo simply describes the shelf as new.

Estante usually means shelf.

If you mean a whole set of shelves or a shelving unit/bookcase, Spanish often uses:

• estantería

So:

• un estante = a shelf
• una estantería = a bookcase / shelving unit

In your sentence, un estante nuevo most naturally means a new shelf.

Para here shows purpose or intended use.

So:

• un estante para mis libros = a shelf for my books

It tells us what the shelf is meant for.

This is a very common use of para:

• una caja para fotos = a box for photos
• una mesa para estudiar = a table for studying
• un regalo para mi amigo = a gift for my friend

Because de español means about Spanish or for Spanish study.

So:

• libros de español = Spanish books / books for learning or studying Spanish

But:

• libros españoles = Spanish books in the sense of books from Spain or Spanish-produced books

That is a very important difference.

So in your sentence, libros de español is the natural choice if you mean textbooks, grammar books, dictionaries, or other books related to the Spanish language.

Because when Spanish names a subject, field, or language after de, it often does not use the article.

So these are normal:

• libro de español = Spanish book / Spanish textbook
• profesor de inglés = English teacher
• clase de historia = history class

Using del español would usually change the meaning or sound less natural here.

So libros de español is the standard expression.

It describes libros, not estante.

The structure is:

• un estante nuevo
• para mis libros de español

So the shelf is for the books, and those books are Spanish books / books for Spanish study.

In other words:

• [estante] = shelf
• para [mis libros de español] = for my Spanish books

A learner might momentarily wonder whether it means a Spanish shelf, but grammatically and logically it clearly means books of Spanish.

Yes. Spanish word order is flexible.

These are all possible:

• En mi cuarto quiero poner un estante nuevo para mis libros de español.
• Quiero poner un estante nuevo en mi cuarto para mis libros de español.
• Quiero poner en mi cuarto un estante nuevo para mis libros de español.

They all mean basically the same thing, but the emphasis shifts slightly.

The original sentence emphasizes the location first:

• En mi cuarto...

That sounds like: As for my room / In my room, I want to...

Yes. Colocar also works well here.

Compare:

• Quiero poner un estante nuevo...
• Quiero colocar un estante nuevo...

Both are correct.

The difference is mostly one of style:

• poner = more common, everyday, broad meaning
• colocar = slightly more precise or a bit more formal, often to place/position

If the shelf is being attached to the wall, some speakers might also say:

• instalar un estante

But poner is the most natural general-purpose verb here.

Not necessarily. It is singular because the speaker means my room as one specific room.

Spanish uses the singular exactly as English does here:

• mi cuarto = my room
• mis cuartos = my rooms

So the sentence is simply referring to one room, presumably the speaker’s bedroom or personal room.

Yes, it sounds natural in Spain.

A speaker from Spain might also say things like:

• En mi habitación quiero poner un estante nuevo para mis libros de español.
• Quiero poner una estantería en mi cuarto para los libros de español.

But your original sentence is perfectly normal and understandable in Peninsular Spanish.