se puso a

started to

→ se
phrase Common #5,787
started to Used before an infinitive to say that someone began doing something.
SP: En cuanto llegó a casa, se puso a cocinar.
EN: As soon as he got home, he started to cook.

Cuando me vio, se puso a correr.

When he saw me, he started running.

Y cuando se lo dije, se puso a escribir en la pared.

And when I told him, he started writing on the wall.

— La piel que habito (2011)

De repente, un perro se puso a ladrar.

Suddenly, a dog started barking.

El profesor se quedó dormido durante la clase y se puso a roncar fuerte.

The teacher fell asleep during class and started snoring loudly.

Cuando Mary vio a Tom desnudo, se puso a reír.

When Mary saw Tom naked, she started laughing.

Eres tú quien se puso a jugar con las especias.

You're the one who started playing with the spices.

— Ratatouille (2007)

Nada más llegar a casa se puso a preparar la comida.

As soon as she got home, she started preparing the food.

Tom se puso a pintar.

Tom started painting.

A pesar de que Tom aún tenía lágrimas en los ojos, se puso a sonreír.

Even though Tom still had tears in his eyes, he started to smile.

Tom se puso a correr.

Tom started running.

Tom se puso a toser.

Tom started coughing.

Un extraño se puso a hablarme.

A stranger started talking to me.

Se puso a silbar una melodía.

He started whistling a tune.

Tom sacó un lápiz y se puso a escribir.

Tom took out a pencil and started writing.

El niño se puso a meter boche.

The boy started to make a fuss.

Tom se puso a pelear con la gente que lo estaba observando.

Tom started fighting with the people who were watching him.

Sus manos temblaban ligeramente cuando se puso a hablar.

His hands trembled slightly when he began to speak.

Mi madre se puso a coser.

My mother started sewing.

De pronto la novia se puso a reír a carcajadas.

Suddenly the bride burst out laughing.

Él perdió la compostura y se puso a arrojar cosas.

He lost his temper and started throwing things.

Se puso a mear desde la galería sobre el sombrero de Biondi.

He started peeing from the gallery onto Biondi's hat.

— Amarcord (1973)