Quiero aprender a coser porque mi camisa vieja se ha roto.

In Spanish, aprender is normally followed by a + infinitive when you mean to learn how to do something.

• aprender a coser = to learn to sew / to learn how to sew
• aprender a nadar = to learn to swim
• aprender a cocinar = to learn to cook

So Quiero aprender a coser is the natural way to say I want to learn to sew.

These are two different verbs:

• coser = to sew
• cocer = to cook / boil

They look very similar, so learners often confuse them.

Examples:

• Voy a coser un botón. = I’m going to sew a button on.
• Voy a cocer pasta. = I’m going to boil pasta.

In pronunciation, in most of Spain:

• coser sounds with an s
• cocer has the c pronounced like the th in think

So they are also pronounced differently in Spain.

Here porque means because. It introduces the reason:

• Quiero aprender a coser porque mi camisa vieja se ha roto.
• I want to learn to sew because my old shirt has torn.

A very common learner issue is mixing up:

• porque = because
• por qué = why
• el porqué = the reason
• por que = less common combination in other structures

In this sentence, the one-word form porque is correct because it gives the cause.

In Spanish, adjectives usually come after the noun, so:

• camisa vieja = old shirt

That is the normal, neutral order.

If you put vieja before the noun, mi vieja camisa, it can sound more literary, emotional, or subjective depending on context. Sometimes a pre-noun adjective gives a more expressive feel, while the post-noun adjective is more factual.

So for a straightforward sentence, mi camisa vieja is the most natural choice.

Usually vieja means old in the sense that the shirt is not new. Depending on context, it can also suggest that it is worn, used a lot, or past its best.

In this sentence, since the shirt se ha roto, the idea is probably:

• it is an old shirt
• and now it has torn

If you wanted to be more explicit about condition, you could say:

• mi camisa está vieja = my shirt is old / worn out
• mi camisa está rota = my shirt is torn

Romper can be used in different ways.

• ha roto usually needs a subject doing the action to something

  • Juan ha roto la camisa. = Juan has torn the shirt.

• se ha roto means it has broken / torn

  • La camisa se ha roto. = The shirt has torn / The shirt got torn.

In your sentence, the shirt is not presented as something that someone deliberately tore. The idea is that it ended up torn, so Spanish commonly uses romperse:

• Mi camisa vieja se ha roto.

This is very natural Spanish.

Here se is part of the pronominal verb romperse, which often means to get broken, to break, or for clothes, to tear.

It does not mean himself/herself here. It is not reflexive in the literal English sense. Instead, it helps express that something became broken/torn.

Compare:

• He roto la camisa. = I have torn the shirt.
• La camisa se ha roto. = The shirt has torn / The shirt got torn.

So se is part of the structure that shifts the focus away from a person causing the damage and onto the result.

Se ha roto is the present perfect, while se rompió is the preterite.

In Spain, the present perfect is often used for a recent past action that still feels connected to the present:

• se ha roto = it has torn / it has become torn

That fits well here, because the shirt being torn is still relevant now: that is the reason the speaker wants to learn sewing.

In many parts of Latin America, people might more naturally say:

• mi camisa vieja se rompió

But in Spain, se ha roto is very common in this kind of context.

Because querer + infinitive does not use a.

• Quiero aprender = I want to learn
• Quiero comer = I want to eat
• Quiero salir = I want to go out

The a belongs with aprender a coser, not with quiero.

So the structure is:

• Quiero
  • aprender a coser

Not:

• Quiero a aprender a coser

Normally, no. The standard structure is aprender a + infinitive when you mean learning how to do something.

So:

• Quiero aprender a coser. ✅
• Quiero aprender coser. ❌

You can, however, use aprender directly with a noun:

• Quiero aprender español. = I want to learn Spanish.
• Quiero aprender la canción. = I want to learn the song.

But with an action verb, Spanish usually wants a:

• aprender a coser
• aprender a conducir
• aprender a bailar

Not exactly.

• coser = to sew in a general sense
• zurcir = to darn / mend, especially repairing a tear or hole in fabric

In this sentence, coser is broad and natural: the speaker wants to learn sewing.

If the idea were specifically to repair the torn shirt, zurcir could sometimes fit, but it is narrower and less general. Coser is the better choice if the person means learning the skill overall.

Yes, but the meaning changes slightly.

• Mi camisa vieja se ha roto. = My old shirt has torn / got torn.
  Focus: the event or change.

• Mi camisa vieja está rota. = My old shirt is torn.
  Focus: the current state.

Both are possible depending on what you want to emphasize. In your sentence, se ha roto works well because it explains the reason for wanting to learn sewing: the shirt has recently torn.

Modern standard Spanish uses mi directly before the noun:

• mi camisa = my shirt

You do not say la mi camisa in normal modern Spanish. That sounds archaic or dialectal.

So:

• mi camisa vieja = my old shirt

Other possessives work the same way:

• tu camisa = your shirt
• su camisa = his/her/your/their shirt
• nuestra camisa = our shirt

A rough pronunciation guide for Spain would be:

KYE-ro a-pren-DER a ko-SER por-KE mi ka-MEE-sa BYE-kha se a RO-to

A few important points:

• quiero begins with a sound like kyeh
• coser has s
• vieja in Spain has the strong j sound, like a throaty h
• ha is very light; the h is silent
• roto has a tapped Spanish r

Also, in much of Spain:

• c before e/i sounds like th in think
• but here in coser, the c is before o, so it sounds like k

Yes, it is very natural.

Quiero aprender a coser porque mi camisa vieja se ha roto.

Why it sounds natural:

• Quiero + infinitive is standard
• aprender a coser is the correct structure
• porque correctly introduces the reason
• mi camisa vieja is a normal noun + adjective order
• se ha roto is especially natural in Spain for a recent event with present relevance

A Spaniard would understand it immediately, and it sounds idiomatic.